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BREW-PDM-CVE-2026-63349 (GHSA-3W57-8XMC-8V26)

Vulnerability from osv_homebrew – Published: 2026-09-19 11:21 – Updated: 2026-09-19 11:21 – Source website
VLAI
Summary
AnyIO run_process/open_process ignores extra_groups and can retain parent supplementary groups
Details

AnyIO 4.14.0 accepts the POSIX extra_groups argument on anyio.run_process() and anyio.open_process(), but open_process() forwards the wrong variable to the backend: when extra_groups is not None, it assigns kwargs["extra_groups"] = group instead of extra_groups. As a result, callers cannot reliably clear or set supplementary groups for child processes. In a disposable Linux container, Python's subprocess.run(..., extra_groups=[]) clears a synthetic parent supplementary group list, while anyio.run_process(..., extra_groups=[]) preserves the parent groups. If group is also supplied, AnyIO passes an integer as extra_groups and the call fails with TypeError. This is a POSIX privilege-dropping correctness issue for applications that rely on AnyIO subprocess helpers to launch less-privileged child processes.

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

{
  "affected": [
    {
      "ecosystem_specific": {
        "fix": "bump",
        "range_state": "fixed",
        "resource": "anyio",
        "resource_purl": "pkg:pypi/anyio@4.15.1",
        "upstream_fixed_in": "4.14.2"
      },
      "package": {
        "ecosystem": "Homebrew",
        "name": "pdm",
        "purl": "pkg:brew/pdm"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.27.0_1"
            },
            {
              "fixed": "2.28.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "confidence": "high",
    "source": "matched",
    "strategy": "registry",
    "upstream_evidence": [
      {
        "ecosystem": "PyPI",
        "key": "pkg:pypi/anyio@4.15.1",
        "name": "anyio",
        "resource": "anyio",
        "strategy": "registry",
        "subject_version": "4.15.1"
      }
    ]
  },
  "details": "AnyIO 4.14.0 accepts the POSIX extra_groups argument on anyio.run_process() and anyio.open_process(), but open_process() forwards the wrong variable to the backend: when extra_groups is not None, it assigns kwargs[\"extra_groups\"] = group instead of extra_groups. As a result, callers cannot reliably clear or set supplementary groups for child processes. In a disposable Linux container, Python\u0027s subprocess.run(..., extra_groups=[]) clears a synthetic parent supplementary group list, while anyio.run_process(..., extra_groups=[]) preserves the parent groups. If group is also supplied, AnyIO passes an integer as extra_groups and the call fails with TypeError. This is a POSIX privilege-dropping correctness issue for applications that rely on AnyIO subprocess helpers to launch less-privileged child processes.",
  "id": "BREW-pdm-CVE-2026-63349",
  "modified": "2026-09-19T11:21:48Z",
  "published": "2026-09-19T11:21:48Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/agronholm/anyio/security/advisories/GHSA-3w57-8xmc-8v26"
    },
    {
      "type": "WEB",
      "url": "https://github.com/agronholm/anyio/pull/1209"
    },
    {
      "type": "WEB",
      "url": "https://github.com/agronholm/anyio/commit/eb562e6462ee46b1904e50b02ce00a858cdeb200"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/agronholm/anyio"
    },
    {
      "type": "WEB",
      "url": "https://github.com/agronholm/anyio/releases/tag/4.14.2"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "AnyIO run_process/open_process ignores extra_groups and can retain parent supplementary groups",
  "upstream": [
    "GHSA-3w57-8xmc-8v26",
    "CVE-2026-63349"
  ]
}



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