BREW-VIRTUALENV-CVE-2026… (CVE-2026-102938)

Vulnerability from osv_homebrew – Published: 2026-10-05 19:15 – Updated: 2026-10-05 19:15 – Source website
VLAI
Summary
virtualenv writes prompt values into pyvenv.cfg without sanitizing line boundaries, allowing configuration injection
Details

virtualenv is a tool for creating isolated virtual python environments. Prior to 21.7.11, PyEnvCfg.write() writes prompt values verbatim to the line-oriented pyvenv.cfg format while PyEnvCfg._read_values() parses the file with str.splitlines() and accepts the last value for duplicate keys. An attacker who influences --prompt, VIRTUALENV_PROMPT, or configuration input can insert a recognized line boundary and additional keys, including home, causing consumers to use an attacker-selected base interpreter or corrupted environment metadata. The security impact requires prompt input from outside the operator's trust boundary; directly supplied prompt content primarily corrupts the operator's own environment. This issue is fixed in version 21.7.11.

Severity
5.8 (Medium)
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "fix": "bump",
        "range_state": "fixed",
        "upstream_fixed_in": "21.7.11"
      },
      "package": {
        "ecosystem": "Homebrew",
        "name": "virtualenv",
        "purl": "pkg:brew/virtualenv"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "20.4.3"
            },
            {
              "fixed": "21.7.11"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "confidence": "high",
    "source": "matched",
    "strategy": "git",
    "upstream_evidence": [
      {
        "ecosystem": "GIT",
        "key": "https://github.com/pypa/virtualenv",
        "name": "https://github.com/pypa/virtualenv",
        "strategy": "git",
        "subject_version": "21.14.5"
      },
      {
        "ecosystem": "PyPI",
        "key": "pkg:pypi/virtualenv@21.14.5",
        "name": "virtualenv",
        "strategy": "registry",
        "subject_version": "21.14.5"
      },
      {
        "ecosystem": "Debian",
        "key": "Debian/python-virtualenv",
        "name": "python-virtualenv",
        "strategy": "distro"
      },
      {
        "ecosystem": "GIT",
        "key": "upstream:https://github.com/pypa/virtualenv",
        "name": "https://github.com/pypa/virtualenv",
        "strategy": "distro",
        "subject_version": "21.14.5"
      },
      {
        "ecosystem": "PyPI",
        "key": "upstream:pkg:pypi/virtualenv@21.14.5",
        "name": "virtualenv",
        "strategy": "distro",
        "subject_version": "21.14.5"
      },
      {
        "ecosystem": "Ubuntu",
        "key": "Ubuntu/python-virtualenv",
        "name": "python-virtualenv",
        "strategy": "distro"
      }
    ]
  },
  "details": "virtualenv is a tool for creating isolated virtual python environments. Prior to 21.7.11, PyEnvCfg.write() writes prompt values verbatim to the line-oriented pyvenv.cfg format while PyEnvCfg._read_values() parses the file with str.splitlines() and accepts the last value for duplicate keys. An attacker who influences --prompt, VIRTUALENV_PROMPT, or configuration input can insert a recognized line boundary and additional keys, including home, causing consumers to use an attacker-selected base interpreter or corrupted environment metadata. The security impact requires prompt input from outside the operator\u0027s trust boundary; directly supplied prompt content primarily corrupts the operator\u0027s own environment. This issue is fixed in version 21.7.11.",
  "id": "BREW-virtualenv-CVE-2026-102938",
  "modified": "2026-10-05T19:15:39Z",
  "published": "2026-10-05T19:15:39Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/pypa/virtualenv/releases/tag/21.7.11"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/102xxx/CVE-2026-102938.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/pypa/virtualenv/security/advisories/GHSA-9h9j-4vrj-gf7g"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-102938"
    },
    {
      "type": "FIX",
      "url": "https://github.com/pypa/virtualenv/commit/a30f995461043acb6cacbf3a890951563ccf7140"
    },
    {
      "type": "FIX",
      "url": "https://github.com/pypa/virtualenv/pull/3247"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "virtualenv writes prompt values into pyvenv.cfg without sanitizing line boundaries, allowing configuration injection",
  "upstream": [
    "CVE-2026-102938",
    "GHSA-9h9j-4vrj-gf7g",
    "PYSEC-2026-4012"
  ]
}



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