GHSA-X78J-V8H9-3J2Q

Vulnerability from github – Published: 2026-10-01 15:08 – Updated: 2026-10-01 15:08
VLAI
Summary
virtualenv: Command injection via --prompt in activate.bat (batch activator)
Details

BatchActivator.quote() returned its input unchanged, the only activator with no escaping at all. --prompt, the VIRTUALENV_PROMPT environment variable, and the config file all set the prompt, and activate.bat writes it straight into @set "VAR=value". A prompt containing a double quote closes that string early, and whatever follows runs as live cmd.exe syntax:

$ virtualenv --prompt 'x" & calc & "' venv
$ venv\Scripts\activate.bat

runs calc the moment someone activates the environment. Confirmed on a real Windows runner. Anyone who templates a prompt from untrusted input (a CI job using a branch name, a wrapper script deriving an environment name from user input) hands an attacker code execution in the shell of anyone who activates the resulting venv on Windows.

Fixed in 21.7.12 by escaping the characters cmd.exe treats as live syntax inside this construct. Fix: https://github.com/pypa/virtualenv/pull/3250

Severity
7.3 (High)
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Show details on source website
To clipboard 

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 21.7.11"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "virtualenv"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "21.7.12"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-102937"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-78"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-01T15:08:29Z",
    "nvd_published_at": "2026-09-29T21:17:18Z",
    "severity": "HIGH"
  },
  "details": "`BatchActivator.quote()` returned its input unchanged, the only activator with no escaping at all. `--prompt`, the `VIRTUALENV_PROMPT` environment variable, and the config file all set the prompt, and `activate.bat` writes it straight into `@set \"VAR=value\"`. A prompt containing a double quote closes that string early, and whatever follows runs as live cmd.exe syntax:\n\n```console\n$ virtualenv --prompt \u0027x\" \u0026 calc \u0026 \"\u0027 venv\n$ venv\\Scripts\\activate.bat\n```\n\nruns `calc` the moment someone activates the environment. Confirmed on a real Windows runner. Anyone who templates a prompt from untrusted input (a CI job using a branch name, a wrapper script deriving an environment name from user input) hands an attacker code execution in the shell of anyone who activates the resulting venv on Windows.\n\nFixed in 21.7.12 by escaping the characters cmd.exe treats as live syntax inside this construct. Fix: https://github.com/pypa/virtualenv/pull/3250",
  "id": "GHSA-x78j-v8h9-3j2q",
  "modified": "2026-10-01T15:08:30Z",
  "published": "2026-10-01T15:08:29Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/pypa/virtualenv/security/advisories/GHSA-x78j-v8h9-3j2q"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-102937"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/virtualenv/pull/3250"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/virtualenv/commit/d721ff140ce4afdc2a9b76751e4584e25d9fbea6"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/virtualenv/PYSEC-2026-4014.yaml"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/pypa/virtualenv"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/virtualenv/releases/tag/21.7.12"
    },
    {
      "type": "WEB",
      "url": "https://pypi.org/project/virtualenv"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "virtualenv: Command injection via --prompt in activate.bat (batch activator)"
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.



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.