PYSEC-2026-4231

Vulnerability from pysec - Published: 2026-10-15 10:22 - Updated: 2026-10-15 14:37
VLAI
Details

Summary

Langflow's built-in Python interpreter components — PythonREPLComponent (Python Interpreter) and the legacy PythonREPLToolComponent (Python REPL Tool) — executed arbitrary user- or model-supplied Python code inside flows without effective sandboxing. Because the code ran in-process with the privileges of the Langflow service, any authenticated user who could edit and run a flow could achieve remote code execution and, from there, escalate privileges to superuser (e.g. by opening a database session and flipping is_superuser) or compromise the host.

This issue is fixed as of 1.10.1, with additional hardening through 1.12.3. See Remediation below.

Affected

  • Package: langflow (PyPI), and the underlying lfx package that ships the component.
  • Vulnerable versions: < 1.10.1.
  • Patched: 1.10.1 (core fix). Upgrade to >= 1.12.3 for the complete hardening series.

Details

The root cause is code injection (CWE-94/CWE-95): the component passed raw input to LangChain's PythonREPL, which is explicitly not a security sandbox.

Two distinct weaknesses existed before 1.10.1:

  1. Unrestricted builtins (default deployments). get_globals() built the exec globals from the global_imports allow-list but never set __builtins__. CPython's exec() then auto-injected the full builtins module, leaving __import__, open, eval, exec and the whole import machinery reachable regardless of the allow-list — e.g. __import__("os").system(...) or __import__("subprocess").check_output([...]). This made the "only modules in Global Imports can be used" guarantee false, and it applied even with the default configuration (allow_custom_components=True).

  2. No server-policy gate (locked-down deployments). Even a deployment hardened with allow_custom_components=False could still run interpreter code, because the components did not consult that policy before executing.

Both let an authenticated user run the reported PoC, which opens a DB session and sets is_superuser = True on their account, or writes to the filesystem / runs OS commands with the service's privileges.

PoC (as reported)

  1. Authenticate as a normal user.
  2. Create a flow with the PythonREPLComponent.
  3. Execute Python that imports Langflow internals and elevates the account:
import asyncio
from sqlmodel import select
from langflow.services.database.models.user.model import User
from langflow.services.deps import session_scope

async def escalate():
    async with session_scope() as session:
        stmt = select(User).where(User.username == 'testuser')
        user = (await session.exec(stmt)).first()
        if user:
            user.is_superuser = True
            session.add(user)
            await session.commit()

asyncio.run(escalate())

Impact

Any authenticated user could: - Execute arbitrary Python / OS commands with the Langflow service's privileges (RCE). - Escalate their own account to superuser via direct database access. - Read/modify data and configuration, and potentially pivot to the underlying host.

Remediation

Upgrade to Langflow 1.10.1 or later (preferably >= 1.12.3). The interpreter components were hardened with layered, defense-in-depth controls, applied in run_python_repl() before any code is executed:

  • Restricted builtins — get_globals() injects a curated safe_builtins() mapping, removing __import__, eval, exec, compile, open, input, globals/locals/vars, getattr/setattr, etc. (#13397)
  • AST validation — validate_code_safety() rejects inline import/from ... import, dunder/escape-gadget attribute access (__class__, __subclasses__, __globals__, frame/traceback introspection) and format-string dunder traversal. (#13397)
  • Server-policy gate — ensure_code_execution_enabled() refuses to run when allow_custom_components=False or block_code_interpreter_components=True, and fails closed if the settings stack cannot be resolved. (#13700 — this advisory — and #14375)
  • Allow-listed module proxies — imported modules are exposed via a proxy that blocks reaching sys.modules["os"] through a module's transitive import graph. (#15198)
  • Optional hardware isolation — configure LANGFLOW_SANDBOX_BACKEND to run interpreter code in an isolated microVM instead of in-process. (#14400)

Upstream fix references: #13397, #13700 (carries this GHSA), #14375, #14400, #15198.

Hardening recommendations for operators

  • Keep Langflow updated (>= 1.12.3).
  • For locked-down deployments, set LANGFLOW_ALLOW_CUSTOM_COMPONENTS=false (or LANGFLOW_BLOCK_CODE_INTERPRETER_COMPONENTS=true) to disable the interpreter entirely.
  • For deployments that must run untrusted code, configure LANGFLOW_SANDBOX_BACKEND for microVM isolation.
  • Run the Langflow service as an unprivileged user with least-privilege database credentials.
Severity
9.9 (Critical)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Impacted products
Name purl
langflow pkg:pypi/langflow
Aliases
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "langflow",
        "purl": "pkg:pypi/langflow"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
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            {
              "fixed": "1.10.1"
            }
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  ],
  "aliases": [
    "CVE-2026-10561",
    "GHSA-8qpj-27x8-pwpq"
  ],
  "details": "### Summary\n\nLangflow\u0027s built-in Python interpreter components \u2014 `PythonREPLComponent` (Python Interpreter) and the legacy `PythonREPLToolComponent` (Python REPL Tool) \u2014 executed arbitrary user- or model-supplied Python code inside flows without effective sandboxing. Because the code ran in-process with the privileges of the Langflow service, any **authenticated** user who could edit and run a flow could achieve remote code execution and, from there, escalate privileges to superuser (e.g. by opening a database session and flipping `is_superuser`) or compromise the host.\n\n**This issue is fixed as of 1.10.1**, with additional hardening through 1.12.3. See *Remediation* below.\n\n### Affected\n\n- **Package:** `langflow` (PyPI), and the underlying `lfx` package that ships the component.\n- **Vulnerable versions:** `\u003c 1.10.1`.\n- **Patched:** `1.10.1` (core fix). Upgrade to `\u003e= 1.12.3` for the complete hardening series.\n\n### Details\n\nThe root cause is **code injection** (CWE-94/CWE-95): the component passed raw input to LangChain\u0027s `PythonREPL`, which is explicitly *not* a security sandbox.\n\nTwo distinct weaknesses existed before 1.10.1:\n\n1. **Unrestricted builtins (default deployments).** `get_globals()` built the `exec` globals from the `global_imports` allow-list but never set `__builtins__`. CPython\u0027s `exec()` then auto-injected the full `builtins` module, leaving `__import__`, `open`, `eval`, `exec` and the whole import machinery reachable regardless of the allow-list \u2014 e.g. `__import__(\"os\").system(...)` or `__import__(\"subprocess\").check_output([...])`. This made the \"only modules in Global Imports can be used\" guarantee false, and it applied even with the **default** configuration (`allow_custom_components=True`).\n\n2. **No server-policy gate (locked-down deployments).** Even a deployment hardened with `allow_custom_components=False` could still run interpreter code, because the components did not consult that policy before executing.\n\nBoth let an authenticated user run the reported PoC, which opens a DB session and sets `is_superuser = True` on their account, or writes to the filesystem / runs OS commands with the service\u0027s privileges.\n\n### PoC (as reported)\n\n1. Authenticate as a normal user.\n2. Create a flow with the `PythonREPLComponent`.\n3. Execute Python that imports Langflow internals and elevates the account:\n\n```python\nimport asyncio\nfrom sqlmodel import select\nfrom langflow.services.database.models.user.model import User\nfrom langflow.services.deps import session_scope\n\nasync def escalate():\n    async with session_scope() as session:\n        stmt = select(User).where(User.username == \u0027testuser\u0027)\n        user = (await session.exec(stmt)).first()\n        if user:\n            user.is_superuser = True\n            session.add(user)\n            await session.commit()\n\nasyncio.run(escalate())\n```\n\n### Impact\n\nAny authenticated user could:\n- Execute arbitrary Python / OS commands with the Langflow service\u0027s privileges (RCE).\n- Escalate their own account to superuser via direct database access.\n- Read/modify data and configuration, and potentially pivot to the underlying host.\n\n### Remediation\n\nUpgrade to **Langflow 1.10.1 or later** (preferably **\u003e= 1.12.3**). The interpreter components were hardened with layered, defense-in-depth controls, applied in `run_python_repl()` before any code is executed:\n\n- **Restricted builtins** \u2014 `get_globals()` injects a curated `safe_builtins()` mapping, removing `__import__`, `eval`, `exec`, `compile`, `open`, `input`, `globals`/`locals`/`vars`, `getattr`/`setattr`, etc. (#13397)\n- **AST validation** \u2014 `validate_code_safety()` rejects inline `import`/`from ... import`, dunder/escape-gadget attribute access (`__class__`, `__subclasses__`, `__globals__`, frame/traceback introspection) and format-string dunder traversal. (#13397)\n- **Server-policy gate** \u2014 `ensure_code_execution_enabled()` refuses to run when `allow_custom_components=False` or `block_code_interpreter_components=True`, and **fails closed** if the settings stack cannot be resolved. (#13700 \u2014 this advisory \u2014 and #14375)\n- **Allow-listed module proxies** \u2014 imported modules are exposed via a proxy that blocks reaching `sys.modules[\"os\"]` through a module\u0027s transitive import graph. (#15198)\n- **Optional hardware isolation** \u2014 configure `LANGFLOW_SANDBOX_BACKEND` to run interpreter code in an isolated microVM instead of in-process. (#14400)\n\nUpstream fix references: #13397, #13700 (carries this GHSA), #14375, #14400, #15198.\n\n### Hardening recommendations for operators\n\n- Keep Langflow updated (\u003e= 1.12.3).\n- For locked-down deployments, set `LANGFLOW_ALLOW_CUSTOM_COMPONENTS=false` (or `LANGFLOW_BLOCK_CODE_INTERPRETER_COMPONENTS=true`) to disable the interpreter entirely.\n- For deployments that must run untrusted code, configure `LANGFLOW_SANDBOX_BACKEND` for microVM isolation.\n- Run the Langflow service as an unprivileged user with least-privilege database credentials.",
  "id": "PYSEC-2026-4231",
  "modified": "2026-10-15T14:37:44.966856Z",
  "published": "2026-10-15T10:22:46.547882Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/langflow-ai/langflow/security/advisories/GHSA-8qpj-27x8-pwpq"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-10561"
    },
    {
      "type": "WEB",
      "url": "https://github.com/langflow-ai/langflow/pull/13700"
    },
    {
      "type": "WEB",
      "url": "https://github.com/langflow-ai/langflow/commit/2754c84aad1306f463db1c3bbb3e8ffbe85da77d"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/langflow-ai/langflow"
    },
    {
      "type": "WEB",
      "url": "https://github.com/langflow-ai/langflow/releases/tag/v1.10.1"
    },
    {
      "type": "WEB",
      "url": "https://www.ibm.com/support/pages/node/7277242"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/langflow"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-8qpj-27x8-pwpq"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Langflow: PythonREPLComponent executes unsandboxed Python code, enabling authenticated RCE and privilege escalation"
}



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