Vulnerability-Lookup

BREW-TERN-CVE-2026-87817 (PYSEC-2026-3982)

Vulnerability from osv_homebrew – Published: 2026-09-20 12:19 – Updated: 2026-10-01 11:08 – Source website

Summary

GitPython: Repository content can impersonate the git directory, leading to arbitrary code execution

Details

Summary

Repo.__init__ decides which directory is the git directory by testing candidate paths in an order that considers the real .git last. Two earlier tests can be satisfied by ordinary tracked files. Git reserves only the literal name .git, so HEAD, objects/, refs/, config, gitdir, commondir and hooks/ at a repository root are all legal tracked content.

Consequently, after a victim opens or clones an attacker's repository, GitPython resolves git_dir to the working-tree root while real git correctly resolves <root>/.git. Everything GitPython then treats as "inside the git directory" is attacker-authored content — including hooks/, which it executes.

CVE-2026-87817

Affected code (3.1.59)

The discovery loop in git/repo/base.py tests, in order:

git/repo/base.py:299 — isfile(curpath/gitdir) and isfile(curpath/commondir) and isfile(curpath/HEAD)
git/repo/base.py:320 — is_git_dir(curpath)
git/repo/base.py:341 — dotgit = osp.join(curpath, ".git") ← the real git dir, considered last

is_git_dir (git/repo/fun.py:60) requires only that objects/ and refs/ are directories and that HEAD is a file; HEAD's contents are never parsed. The hook path is resolved from index.repo.git_dir (git/index/fun.py:73), i.e. the mis-resolved directory.

Proof of concept

Requires only pip install GitPython==3.1.59. Full script attached as poc1_rce.py; it runs entirely in a temp directory and the payload only writes a marker file.

Attacker repository — four ordinary tracked files at the root:

path	mode	content
`gitdir`	100644	`.git\n`
`commondir`	100644	`.git\n`
`HEAD`	100644	`ref: refs/heads/master\n`
`hooks/pre-commit`	100755	`#!/bin/sh` + payload

Victim — two ordinary calls:

repo = git.Repo.clone_from(url, dst)     # or git.Repo(dst)
repo.index.commit("automated commit")    # code execution happens here

Observed on the PyPI release 3.1.59 (Linux and Windows):

real git says the git dir is : /tmp/.../victim/.git
GitPython says it is         : /tmp/.../victim      <- shadowed
attacker's hook executed     : True
git fsck                     : (clean)

The pre-commit hook runs at git/index/base.py:1201, before write_tree(), so it fires even though the commit later fails.

Impact

A service that opens or clones an untrusted repository with GitPython — a CI runner building a fork pull request, a code-scanning/SBOM service, a mirror, a dependency bot, an AI code-review/agent tool — can be made to:

Execute arbitrary commands via the tracked <root>/hooks/pre-commit when the victim calls index.commit().
Read files outside the repository: the tracked <root>/config becomes the repository config and is parsed with merge_includes=True (git/repo/base.py:765), so [include] path = ~/.aws/credentials discloses the file. (Repo._config_reader still defaults merge_includes=True, so the hardening added in 3.1.59 for .gitmodules/GHSA-7833 does not cover this path.)
Write a config file to an attacker-chosen directory via an absolute tracked commondir.

Delivery is silent: git clone exits 0, git fsck (including --strict, and with transfer.fsckObjects/fetch.fsckObjects=true) reports nothing, and the clone passes every read-only probe (head.commit, branches, is_dirty(), untracked_files, iter_commits) because a tracked commondir of .git pins common_dir to the real .git.

Threat model / preconditions

Attacker controls the content of a repository the victim opens or clones with GitPython (public repo, fork PR, mirrored dependency).
For code execution, the victim performs a commit via GitPython's native index.commit(). For the file-read impact, opening the repo and reading config is enough.
GIT_WORK_TREE is not a mitigation — git_dir is assigned and the discovery loop breaks before the environment is consulted.
Real git is unaffected; only GitPython mis-resolves the directory.

Remediation

Test curpath/.git before the gitdir/commondir/HEAD triple and before is_git_dir(curpath).
Resolve hook_path / _commit_hook_path / _get_validated_reflog_path through repo.common_dir.
Containment-check commondir/gitdir contents before joining (reuse SymbolicReference._get_validated_path).
Validate HEAD in is_git_dir (require ref: refs/... or a 40-hex sha).
Pass merge_includes=False in Repo._config_reader (git/repo/base.py:765).

Note for the maintainers

Commit 406b98e1 (2026-05-31, "respect core.hooksPath for commit hooks") resolved the hook path via git rev-parse --git-path, which is immune because git rediscovers the true .git. Commit 9bc287a2 (2026-07-20) reverted it to avoid an unconditional rev-parse dependency — reintroducing the exec step. Measured at each commit with the healthy-looking layout: 406b98e1 → hook did not fire; 9bc287a2 … 3.1.59 → hook fired.

Scope note

Only the repository-root case is reported: where a real .git exists, git prefers it, and GitPython does not. A fake git dir in a subdirectory fools real git too, so that variant is out of scope as a general ecosystem hazard rather than a GitPython defect.

POC Files :

poc1_rce.py poc2_file_read.py

Severity

8.8 (High)


                    
                      CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

References

URL

Type

	https://github.com/gitpython-developers/GitPython…	WEB
	https://nvd.nist.gov/vuln/detail/CVE-2026-87817	ADVISORY
	https://github.com/gitpython-developers/GitPython…	WEB
	https://github.com/gitpython-developers/GitPython…	WEB
	https://github.com/gitpython-developers/GitPython	PACKAGE
	https://github.com/gitpython-developers/GitPython…	WEB
	https://github.com/pypa/advisory-database/tree/ma…	WEB
	https://www.vulncheck.com/advisories/gitpython-be…	WEB

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "fix": null,
        "range_state": "affected",
        "resource": "gitpython",
        "resource_purl": "pkg:pypi/gitpython@3.1.45",
        "upstream_fixed_in": "3.1.60"
      },
      "package": {
        "ecosystem": "Homebrew",
        "name": "tern",
        "purl": "pkg:brew/tern"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.12.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "confidence": "high",
    "source": "matched",
    "strategy": "registry",
    "upstream_evidence": [
      {
        "ecosystem": "PyPI",
        "key": "pkg:pypi/gitpython@3.1.45",
        "name": "gitpython",
        "resource": "gitpython",
        "strategy": "registry",
        "subject_version": "3.1.45"
      }
    ]
  },
  "details": "### Summary\n\n`Repo.__init__` decides which directory is the git directory by testing candidate paths in an order that\nconsiders the real `.git` **last**. Two earlier tests can be satisfied by ordinary tracked files. Git\nreserves only the literal name `.git`, so `HEAD`, `objects/`, `refs/`, `config`, `gitdir`, `commondir`\nand `hooks/` at a repository root are all legal tracked content.\n\nConsequently, after a victim opens or clones an attacker\u0027s repository, GitPython resolves `git_dir` to\nthe **working-tree root** while real git correctly resolves `\u003croot\u003e/.git`. Everything GitPython then\ntreats as \"inside the git directory\" is attacker-authored content \u2014 including `hooks/`, which it\nexecutes.\n\n### CVE-2026-87817\n\n### Affected code (3.1.59)\n\nThe discovery loop in `git/repo/base.py` tests, in order:\n\n1. `git/repo/base.py:299` \u2014 `isfile(curpath/gitdir)` **and** `isfile(curpath/commondir)` **and** `isfile(curpath/HEAD)`\n2. `git/repo/base.py:320` \u2014 `is_git_dir(curpath)`\n3. `git/repo/base.py:341` \u2014 `dotgit = osp.join(curpath, \".git\")` \u2190 the real git dir, considered last\n\n`is_git_dir` (`git/repo/fun.py:60`) requires only that `objects/` and `refs/` are directories and that\n`HEAD` is a file; **`HEAD`\u0027s contents are never parsed.** The hook path is resolved from\n`index.repo.git_dir` (`git/index/fun.py:73`), i.e. the mis-resolved directory.\n\n### Proof of concept\n\nRequires only `pip install GitPython==3.1.59`. Full script attached as `poc1_rce.py`; it runs entirely\nin a temp directory and the payload only writes a marker file.\n\nAttacker repository \u2014 four ordinary tracked files at the root:\n\n| path | mode | content |\n|---|---|---|\n| `gitdir` | 100644 | `.git\\n` |\n| `commondir` | 100644 | `.git\\n` |\n| `HEAD` | 100644 | `ref: refs/heads/master\\n` |\n| `hooks/pre-commit` | **100755** | `#!/bin/sh` + payload |\n\nVictim \u2014 two ordinary calls:\n\n```python\nrepo = git.Repo.clone_from(url, dst)     # or git.Repo(dst)\nrepo.index.commit(\"automated commit\")    # code execution happens here\n```\n\nObserved on the PyPI release 3.1.59 (Linux and Windows):\n\n```\nreal git says the git dir is : /tmp/.../victim/.git\nGitPython says it is         : /tmp/.../victim      \u003c- shadowed\nattacker\u0027s hook executed     : True\ngit fsck                     : (clean)\n```\n\nThe `pre-commit` hook runs at `git/index/base.py:1201`, before `write_tree()`, so it fires even though\nthe commit later fails.\n\n### Impact\n\nA service that opens or clones an untrusted repository with GitPython \u2014 a CI runner building a fork\npull request, a code-scanning/SBOM service, a mirror, a dependency bot, an AI code-review/agent tool \u2014\ncan be made to:\n\n1. **Execute arbitrary commands** via the tracked `\u003croot\u003e/hooks/pre-commit` when the victim calls\n   `index.commit()`.\n2. **Read files outside the repository**: the tracked `\u003croot\u003e/config` becomes the repository config and\n   is parsed with `merge_includes=True` (`git/repo/base.py:765`), so `[include] path = ~/.aws/credentials`\n   discloses the file. (`Repo._config_reader` still defaults `merge_includes=True`, so the hardening\n   added in 3.1.59 for `.gitmodules`/GHSA-7833 does not cover this path.)\n3. **Write a config file to an attacker-chosen directory** via an absolute tracked `commondir`.\n\nDelivery is silent: `git clone` exits 0, `git fsck` (including `--strict`, and with\n`transfer.fsckObjects`/`fetch.fsckObjects=true`) reports nothing, and the clone passes every read-only\nprobe (`head.commit`, `branches`, `is_dirty()`, `untracked_files`, `iter_commits`) because a tracked\n`commondir` of `.git` pins `common_dir` to the real `.git`.\n\n### Threat model / preconditions\n\n- Attacker controls the content of a repository the victim opens or clones with GitPython (public repo,\n  fork PR, mirrored dependency).\n- For code execution, the victim performs a commit via GitPython\u0027s native `index.commit()`. For the\n  file-read impact, opening the repo and reading config is enough.\n- `GIT_WORK_TREE` is **not** a mitigation \u2014 `git_dir` is assigned and the discovery loop breaks before\n  the environment is consulted.\n- Real git is unaffected; only GitPython mis-resolves the directory.\n\n### Remediation\n\n1. Test `curpath/.git` **before** the `gitdir`/`commondir`/`HEAD` triple and before `is_git_dir(curpath)`.\n2. Resolve `hook_path` / `_commit_hook_path` / `_get_validated_reflog_path` through `repo.common_dir`.\n3. Containment-check `commondir`/`gitdir` contents before joining (reuse\n   `SymbolicReference._get_validated_path`).\n4. Validate `HEAD` in `is_git_dir` (require `ref: refs/...` or a 40-hex sha).\n5. Pass `merge_includes=False` in `Repo._config_reader` (`git/repo/base.py:765`).\n\n### Note for the maintainers\n\nCommit `406b98e1` (2026-05-31, \"respect core.hooksPath for commit hooks\") resolved the hook path via\n`git rev-parse --git-path`, which is immune because git rediscovers the true `.git`. Commit `9bc287a2`\n(2026-07-20) reverted it to avoid an unconditional `rev-parse` dependency \u2014 reintroducing the exec step.\nMeasured at each commit with the healthy-looking layout: `406b98e1` \u2192 hook did not fire; `9bc287a2` \u2026\n`3.1.59` \u2192 hook fired.\n\n### Scope note\n\nOnly the **repository-root** case is reported: where a real `.git` exists, git prefers it, and GitPython\ndoes not. A fake git dir in a subdirectory fools real git too, so that variant is out of scope as a\ngeneral ecosystem hazard rather than a GitPython defect.\n\n###POC Files :\n[poc1_rce.py](https://github.com/user-attachments/files/31388464/poc1_rce.py)\n[poc2_file_read.py](https://github.com/user-attachments/files/31388465/poc2_file_read.py)",
  "id": "BREW-tern-CVE-2026-87817",
  "modified": "2026-10-01T11:08:05Z",
  "published": "2026-09-20T12:19:34Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/gitpython-developers/GitPython/security/advisories/GHSA-239g-whfq-7xj9"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-87817"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gitpython-developers/GitPython/pull/2218"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gitpython-developers/GitPython/commit/c7cf4d13b1ed0a2e70f2a1f3c6b4fc6c2652cf0b"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/gitpython-developers/GitPython"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gitpython-developers/GitPython/releases/tag/3.1.60"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/gitpython/PYSEC-2026-3982.yaml"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/gitpython-before-3.1.60-remote-code-execution-via-git-directory-impersonation"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "GitPython: Repository content can impersonate the git directory, leading to arbitrary code execution",
  "upstream": [
    "PYSEC-2026-3982",
    "CVE-2026-87817",
    "GHSA-239g-whfq-7xj9"
  ]
}

CVE-2026-87817 (GCVE-0-2026-87817)

Vulnerability from cvelistv5 – Published: 2026-09-09 11:21 – Updated: 2026-09-10 14:58

Title

GitPython before 3.1.60 Remote Code Execution via Git Directory Impersonation

Summary

GitPython before 3.1.60 fails to properly validate the git directory location, allowing attackers to impersonate the git directory using tracked files like gitdir, commondir, and HEAD. Attackers can execute arbitrary code by placing a malicious pre-commit hook in the tracked hooks directory that executes when a victim calls index.commit() on a cloned or opened repository.

Severity

8.7 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

8.8 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

SSVC

Exploitation: none Automatable: yes Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-10 14:27 UTC

CWE

CWE-94 - Improper Control of Generation of Code ('Code Injection')

Assigner

VulnCheck mitre root Scorecard

References

2 references

URL	Tags
https://github.com/gitpython-developers/GitPython…	vendor-advisory
https://www.vulncheck.com/advisories/gitpython-be…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version
gitpython-developers	GitPython	Affected: 0 , < 3.1.60 (semver) Unaffected: 3.1.60 (semver) cpe:2.3:a:gitpython_project:gitpython::::::::

Date Public

2026-08-26 00:00

Credits

dharanivarma

Show details on NVD website

JSON

To clipboard

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GHSA-239G-WHFQ-7XJ9

Vulnerability from github – Published: 2026-09-30 23:27 – Updated: 2026-09-30 23:27

Summary

GitPython: Repository content can impersonate the git directory, leading to arbitrary code execution

Details

Summary

CVE-2026-87817

Affected code (3.1.59)

The discovery loop in git/repo/base.py tests, in order:

git/repo/base.py:299 — isfile(curpath/gitdir) and isfile(curpath/commondir) and isfile(curpath/HEAD)
git/repo/base.py:320 — is_git_dir(curpath)
git/repo/base.py:341 — dotgit = osp.join(curpath, ".git") ← the real git dir, considered last

Proof of concept

Requires only pip install GitPython==3.1.59. Full script attached as poc1_rce.py; it runs entirely in a temp directory and the payload only writes a marker file.

Attacker repository — four ordinary tracked files at the root:

path	mode	content
`gitdir`	100644	`.git\n`
`commondir`	100644	`.git\n`
`HEAD`	100644	`ref: refs/heads/master\n`
`hooks/pre-commit`	100755	`#!/bin/sh` + payload

Victim — two ordinary calls:

repo = git.Repo.clone_from(url, dst)     # or git.Repo(dst)
repo.index.commit("automated commit")    # code execution happens here

Observed on the PyPI release 3.1.59 (Linux and Windows):

real git says the git dir is : /tmp/.../victim/.git
GitPython says it is         : /tmp/.../victim      <- shadowed
attacker's hook executed     : True
git fsck                     : (clean)

The pre-commit hook runs at git/index/base.py:1201, before write_tree(), so it fires even though the commit later fails.

Impact

Execute arbitrary commands via the tracked <root>/hooks/pre-commit when the victim calls index.commit().
Read files outside the repository: the tracked <root>/config becomes the repository config and is parsed with merge_includes=True (git/repo/base.py:765), so [include] path = ~/.aws/credentials discloses the file. (Repo._config_reader still defaults merge_includes=True, so the hardening added in 3.1.59 for .gitmodules/GHSA-7833 does not cover this path.)
Write a config file to an attacker-chosen directory via an absolute tracked commondir.

Threat model / preconditions

Attacker controls the content of a repository the victim opens or clones with GitPython (public repo, fork PR, mirrored dependency).
For code execution, the victim performs a commit via GitPython's native index.commit(). For the file-read impact, opening the repo and reading config is enough.
GIT_WORK_TREE is not a mitigation — git_dir is assigned and the discovery loop breaks before the environment is consulted.
Real git is unaffected; only GitPython mis-resolves the directory.

Remediation

Test curpath/.git before the gitdir/commondir/HEAD triple and before is_git_dir(curpath).
Resolve hook_path / _commit_hook_path / _get_validated_reflog_path through repo.common_dir.
Containment-check commondir/gitdir contents before joining (reuse SymbolicReference._get_validated_path).
Validate HEAD in is_git_dir (require ref: refs/... or a 40-hex sha).
Pass merge_includes=False in Repo._config_reader (git/repo/base.py:765).

Note for the maintainers

Scope note

POC Files :

poc1_rce.py poc2_file_read.py

Severity

8.8 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.1.59"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "gitpython"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.1.60"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-87817"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-427",
      "CWE-94"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-30T23:27:59Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Summary\n\n`Repo.__init__` decides which directory is the git directory by testing candidate paths in an order that\nconsiders the real `.git` **last**. Two earlier tests can be satisfied by ordinary tracked files. Git\nreserves only the literal name `.git`, so `HEAD`, `objects/`, `refs/`, `config`, `gitdir`, `commondir`\nand `hooks/` at a repository root are all legal tracked content.\n\nConsequently, after a victim opens or clones an attacker\u0027s repository, GitPython resolves `git_dir` to\nthe **working-tree root** while real git correctly resolves `\u003croot\u003e/.git`. Everything GitPython then\ntreats as \"inside the git directory\" is attacker-authored content \u2014 including `hooks/`, which it\nexecutes.\n\n### CVE-2026-87817\n\n### Affected code (3.1.59)\n\nThe discovery loop in `git/repo/base.py` tests, in order:\n\n1. `git/repo/base.py:299` \u2014 `isfile(curpath/gitdir)` **and** `isfile(curpath/commondir)` **and** `isfile(curpath/HEAD)`\n2. `git/repo/base.py:320` \u2014 `is_git_dir(curpath)`\n3. `git/repo/base.py:341` \u2014 `dotgit = osp.join(curpath, \".git\")` \u2190 the real git dir, considered last\n\n`is_git_dir` (`git/repo/fun.py:60`) requires only that `objects/` and `refs/` are directories and that\n`HEAD` is a file; **`HEAD`\u0027s contents are never parsed.** The hook path is resolved from\n`index.repo.git_dir` (`git/index/fun.py:73`), i.e. the mis-resolved directory.\n\n### Proof of concept\n\nRequires only `pip install GitPython==3.1.59`. Full script attached as `poc1_rce.py`; it runs entirely\nin a temp directory and the payload only writes a marker file.\n\nAttacker repository \u2014 four ordinary tracked files at the root:\n\n| path | mode | content |\n|---|---|---|\n| `gitdir` | 100644 | `.git\\n` |\n| `commondir` | 100644 | `.git\\n` |\n| `HEAD` | 100644 | `ref: refs/heads/master\\n` |\n| `hooks/pre-commit` | **100755** | `#!/bin/sh` + payload |\n\nVictim \u2014 two ordinary calls:\n\n```python\nrepo = git.Repo.clone_from(url, dst)     # or git.Repo(dst)\nrepo.index.commit(\"automated commit\")    # code execution happens here\n```\n\nObserved on the PyPI release 3.1.59 (Linux and Windows):\n\n```\nreal git says the git dir is : /tmp/.../victim/.git\nGitPython says it is         : /tmp/.../victim      \u003c- shadowed\nattacker\u0027s hook executed     : True\ngit fsck                     : (clean)\n```\n\nThe `pre-commit` hook runs at `git/index/base.py:1201`, before `write_tree()`, so it fires even though\nthe commit later fails.\n\n### Impact\n\nA service that opens or clones an untrusted repository with GitPython \u2014 a CI runner building a fork\npull request, a code-scanning/SBOM service, a mirror, a dependency bot, an AI code-review/agent tool \u2014\ncan be made to:\n\n1. **Execute arbitrary commands** via the tracked `\u003croot\u003e/hooks/pre-commit` when the victim calls\n   `index.commit()`.\n2. **Read files outside the repository**: the tracked `\u003croot\u003e/config` becomes the repository config and\n   is parsed with `merge_includes=True` (`git/repo/base.py:765`), so `[include] path = ~/.aws/credentials`\n   discloses the file. (`Repo._config_reader` still defaults `merge_includes=True`, so the hardening\n   added in 3.1.59 for `.gitmodules`/GHSA-7833 does not cover this path.)\n3. **Write a config file to an attacker-chosen directory** via an absolute tracked `commondir`.\n\nDelivery is silent: `git clone` exits 0, `git fsck` (including `--strict`, and with\n`transfer.fsckObjects`/`fetch.fsckObjects=true`) reports nothing, and the clone passes every read-only\nprobe (`head.commit`, `branches`, `is_dirty()`, `untracked_files`, `iter_commits`) because a tracked\n`commondir` of `.git` pins `common_dir` to the real `.git`.\n\n### Threat model / preconditions\n\n- Attacker controls the content of a repository the victim opens or clones with GitPython (public repo,\n  fork PR, mirrored dependency).\n- For code execution, the victim performs a commit via GitPython\u0027s native `index.commit()`. For the\n  file-read impact, opening the repo and reading config is enough.\n- `GIT_WORK_TREE` is **not** a mitigation \u2014 `git_dir` is assigned and the discovery loop breaks before\n  the environment is consulted.\n- Real git is unaffected; only GitPython mis-resolves the directory.\n\n### Remediation\n\n1. Test `curpath/.git` **before** the `gitdir`/`commondir`/`HEAD` triple and before `is_git_dir(curpath)`.\n2. Resolve `hook_path` / `_commit_hook_path` / `_get_validated_reflog_path` through `repo.common_dir`.\n3. Containment-check `commondir`/`gitdir` contents before joining (reuse\n   `SymbolicReference._get_validated_path`).\n4. Validate `HEAD` in `is_git_dir` (require `ref: refs/...` or a 40-hex sha).\n5. Pass `merge_includes=False` in `Repo._config_reader` (`git/repo/base.py:765`).\n\n### Note for the maintainers\n\nCommit `406b98e1` (2026-05-31, \"respect core.hooksPath for commit hooks\") resolved the hook path via\n`git rev-parse --git-path`, which is immune because git rediscovers the true `.git`. Commit `9bc287a2`\n(2026-07-20) reverted it to avoid an unconditional `rev-parse` dependency \u2014 reintroducing the exec step.\nMeasured at each commit with the healthy-looking layout: `406b98e1` \u2192 hook did not fire; `9bc287a2` \u2026\n`3.1.59` \u2192 hook fired.\n\n### Scope note\n\nOnly the **repository-root** case is reported: where a real `.git` exists, git prefers it, and GitPython\ndoes not. A fake git dir in a subdirectory fools real git too, so that variant is out of scope as a\ngeneral ecosystem hazard rather than a GitPython defect.\n\n###POC Files :\n[poc1_rce.py](https://github.com/user-attachments/files/31388464/poc1_rce.py)\n[poc2_file_read.py](https://github.com/user-attachments/files/31388465/poc2_file_read.py)",
  "id": "GHSA-239g-whfq-7xj9",
  "modified": "2026-09-30T23:27:59Z",
  "published": "2026-09-30T23:27:59Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/gitpython-developers/GitPython/security/advisories/GHSA-239g-whfq-7xj9"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-87817"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gitpython-developers/GitPython/pull/2218"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gitpython-developers/GitPython/commit/c7cf4d13b1ed0a2e70f2a1f3c6b4fc6c2652cf0b"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/gitpython-developers/GitPython"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gitpython-developers/GitPython/releases/tag/3.1.60"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/gitpython/PYSEC-2026-3982.yaml"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/gitpython-before-3.1.60-remote-code-execution-via-git-directory-impersonation"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "GitPython: Repository content can impersonate the git directory, leading to arbitrary code execution"
}

PYSEC-2026-3982

Vulnerability from pysec - Published: 2026-09-09 12:17 - Updated: 2026-09-17 08:35

Details

Severity

8.7 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Impacted products

Name	purl
gitpython	pkg:pypi/gitpython

Aliases

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {},
      "package": {
        "ecosystem": "PyPI",
        "name": "gitpython",
        "purl": "pkg:pypi/gitpython"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.1.60"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.1.7",
        "0.2.0-beta1",
        "0.3.0-beta1",
        "0.3.0-beta2",
        "0.3.1-beta2",
        "0.3.2",
        "0.3.2.1",
        "0.3.2.RC1",
        "0.3.3",
        "0.3.4",
        "0.3.5",
        "0.3.6",
        "0.3.7",
        "1.0.0",
        "1.0.1",
        "1.0.2",
        "2.0.0",
        "2.0.1",
        "2.0.2",
        "2.0.3",
        "2.0.4",
        "2.0.5",
        "2.0.6",
        "2.0.7",
        "2.0.8",
        "2.0.9",
        "2.0.9.dev0",
        "2.0.9.dev1",
        "2.1.0",
        "2.1.1",
        "2.1.10",
        "2.1.11",
        "2.1.12",
        "2.1.13",
        "2.1.14",
        "2.1.15",
        "2.1.2",
        "2.1.3",
        "2.1.4",
        "2.1.5",
        "2.1.6",
        "2.1.7",
        "2.1.8",
        "2.1.9",
        "3.0.0",
        "3.0.1",
        "3.0.2",
        "3.0.3",
        "3.0.4",
        "3.0.5",
        "3.0.6",
        "3.0.7",
        "3.0.8",
        "3.0.9",
        "3.1.0",
        "3.1.1",
        "3.1.10",
        "3.1.11",
        "3.1.12",
        "3.1.13",
        "3.1.14",
        "3.1.15",
        "3.1.16",
        "3.1.17",
        "3.1.18",
        "3.1.19",
        "3.1.2",
        "3.1.20",
        "3.1.22",
        "3.1.23",
        "3.1.24",
        "3.1.25",
        "3.1.26",
        "3.1.27",
        "3.1.28",
        "3.1.29",
        "3.1.3",
        "3.1.30",
        "3.1.31",
        "3.1.32",
        "3.1.33",
        "3.1.34",
        "3.1.35",
        "3.1.36",
        "3.1.37",
        "3.1.38",
        "3.1.4",
        "3.1.40",
        "3.1.41",
        "3.1.42",
        "3.1.43",
        "3.1.44",
        "3.1.45",
        "3.1.46",
        "3.1.47",
        "3.1.48",
        "3.1.49",
        "3.1.5",
        "3.1.50",
        "3.1.51",
        "3.1.52",
        "3.1.53",
        "3.1.54",
        "3.1.55",
        "3.1.56",
        "3.1.57",
        "3.1.58",
        "3.1.59",
        "3.1.6",
        "3.1.7",
        "3.1.8",
        "3.1.9"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-87817",
    "GHSA-239g-whfq-7xj9"
  ],
  "details": "GitPython before 3.1.60 fails to properly validate the git directory location, allowing attackers to impersonate the git directory using tracked files like gitdir, commondir, and HEAD. Attackers can execute arbitrary code by placing a malicious pre-commit hook in the tracked hooks directory that executes when a victim calls index.commit() on a cloned or opened repository.",
  "id": "PYSEC-2026-3982",
  "modified": "2026-09-17T08:35:35.862556Z",
  "published": "2026-09-09T12:17:16.830Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.vulncheck.com/advisories/gitpython-before-3.1.60-remote-code-execution-via-git-directory-impersonation"
    },
    {
      "type": "EVIDENCE",
      "url": "https://github.com/gitpython-developers/GitPython/security/advisories/GHSA-239g-whfq-7xj9"
    }
  ],
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

BREW-TERN-CVE-2026-87817 (PYSEC-2026-3982)

Summary

CVE-2026-87817

Affected code (3.1.59)

Proof of concept

Impact

Threat model / preconditions

Remediation

Note for the maintainers

Scope note

POC Files :

CVE-2026-87817 (GCVE-0-2026-87817)

GHSA-239G-WHFQ-7XJ9

Summary

CVE-2026-87817

Affected code (3.1.59)

Proof of concept

Impact

Threat model / preconditions

Remediation

Note for the maintainers

Scope note

POC Files :

PYSEC-2026-3982

Tags

Sightings

Nomenclature

Related by attack behaviour