GHSA-P58F-9548-MPM2

Vulnerability from github – Published: 2026-10-01 15:09 – Updated: 2026-10-01 15:09
VLAI
Summary
virtualenv bash and fish activation scripts execute commands embedded in paths
Details

Impact

The generated activate (bash/zsh) and activate.fish scripts interpolate a shlex.quote-ed value into a position that quotes it a second time. The extra quotes terminate the quoted run early and leave part of the value parsed as shell code, so a path containing shell metacharacters runs commands when a user sources the activation script.

activate is affected through the virtual environment's own path, on the branch that reports a relocated environment:

echo "Virtual environment directory __VIRTUAL_ENV__ does not exist!" >&2

For a destination named x'$(id)'y, shlex.quote emits 'x'"'"'$(id)'"'"'y'. The inner " closes the enclosing double quote and $(id) is left unquoted. Backtick and ; payloads reach the same result. This branch runs whenever the recorded path is absent, which is the normal case for a virtual environment copied or distributed to another machine.

activate.fish is affected through the interpreter's Tcl/Tk library paths:

set -gx TCL_LIBRARY '__TCL_LIBRARY__'

shlex.quote already returns '/tcl/(cmd)/lib', so the rendered line is ''/tcl/(cmd)/lib''. fish concatenates the adjacent quoted runs and expands the (cmd) left between them. The same doubling also splits a path containing a space into two list elements, corrupting TCL_LIBRARY and TK_LIBRARY.

This is the same defect class as GHSA-x78j-v8h9-3j2q, which covered activate.bat.

Patches

Fixed in 21.7.13 by moving the placeholders outside the surrounding quotes, so each value keeps only the quoting shlex.quote applied. Fix: https://github.com/pypa/virtualenv/pull/3252

Workarounds

Avoid creating or distributing virtual environments whose path contains ', `, $, ;, ( or ), and inspect the generated activation script before sourcing one you did not create.

Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 21.7.12"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "virtualenv"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "21.7.13"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-102925"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-78"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-01T15:09:17Z",
    "nvd_published_at": "2026-09-29T21:17:18Z",
    "severity": "HIGH"
  },
  "details": "### Impact\n\nThe generated `activate` (bash/zsh) and `activate.fish` scripts interpolate a `shlex.quote`-ed value into a position that quotes it a second time. The extra quotes terminate the quoted run early and leave part of the value parsed as shell code, so a path containing shell metacharacters runs commands when a user sources the activation script.\n\n`activate` is affected through the virtual environment\u0027s own path, on the branch that reports a relocated environment:\n\n```sh\necho \"Virtual environment directory __VIRTUAL_ENV__ does not exist!\" \u003e\u00262\n```\n\nFor a destination named `x\u0027$(id)\u0027y`, `shlex.quote` emits `\u0027x\u0027\"\u0027\"\u0027$(id)\u0027\"\u0027\"\u0027y\u0027`. The inner `\"` closes the enclosing double quote and `$(id)` is left unquoted. Backtick and `;` payloads reach the same result. This branch runs whenever the recorded path is absent, which is the normal case for a virtual environment copied or distributed to another machine.\n\n`activate.fish` is affected through the interpreter\u0027s Tcl/Tk library paths:\n\n```fish\nset -gx TCL_LIBRARY \u0027__TCL_LIBRARY__\u0027\n```\n\n`shlex.quote` already returns `\u0027/tcl/(cmd)/lib\u0027`, so the rendered line is `\u0027\u0027/tcl/(cmd)/lib\u0027\u0027`. fish concatenates the adjacent quoted runs and expands the `(cmd)` left between them. The same doubling also splits a path containing a space into two list elements, corrupting `TCL_LIBRARY` and `TK_LIBRARY`.\n\nThis is the same defect class as GHSA-x78j-v8h9-3j2q, which covered `activate.bat`.\n\n### Patches\n\nFixed in 21.7.13 by moving the placeholders outside the surrounding quotes, so each value keeps only the quoting `shlex.quote` applied. Fix: https://github.com/pypa/virtualenv/pull/3252\n\n### Workarounds\n\nAvoid creating or distributing virtual environments whose path contains `\u0027`, `` ` ``, `$`, `;`, `(` or `)`, and inspect the generated activation script before sourcing one you did not create.",
  "id": "GHSA-p58f-9548-mpm2",
  "modified": "2026-10-01T15:09:18Z",
  "published": "2026-10-01T15:09:17Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/pypa/virtualenv/security/advisories/GHSA-p58f-9548-mpm2"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-102925"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/virtualenv/pull/3252"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/virtualenv/commit/4d5a105ec2a2723b8c7f4571bb68f4f71d01e3f6"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/virtualenv/PYSEC-2026-4013.yaml"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/pypa/virtualenv"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/virtualenv/releases/tag/21.7.13"
    },
    {
      "type": "WEB",
      "url": "https://pypi.org/project/virtualenv"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "virtualenv bash and fish activation scripts execute commands embedded in paths"
}



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