GHSA-Q38V-WP89-2W55

Vulnerability from github – Published: 2026-07-17 18:41 – Updated: 2026-07-17 18:41
VLAI
Summary
sh _uid does not drop supplementary groups (incomplete privilege drop)
Details

Impact

The _uid option performed an incomplete privilege drop on Linux/Unix-like systems.

When sh was run from a process with elevated privileges, such as root, and a command was launched with _uid=<unprivileged user>, the child process changed its UID and primary GID but did not reset its supplementary groups. As a result, the child process could retain the parent process’s supplementary groups, potentially including privileged groups such as root, docker, disk, shadow, or sudo.

This could allow a subprocess that was expected to run with reduced privileges to access files or resources available to the original process’s supplementary groups. Users are impacted if they rely on _uid as a privilege boundary when launching commands from a privileged parent process.

Patches

Upgrade to version >= 2.2.4

Workarounds

Avoid using _uid when the user represents a less-privileged user.

Severity
7.9 (High)
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "sh"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.2.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-54552"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-273"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-17T18:41:38Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Impact\nThe `_uid` option performed an incomplete privilege drop on Linux/Unix-like systems.\n\nWhen `sh` was run from a process with elevated privileges, such as root, and a command was launched with `_uid=\u003cunprivileged user\u003e`, the child process changed its UID and primary GID but did not reset its supplementary groups. As a result, the child process could retain the parent process\u2019s supplementary groups, potentially including privileged groups such as root, docker, disk, shadow, or sudo.\n\nThis could allow a subprocess that was expected to run with reduced privileges to access files or resources available to the original process\u2019s supplementary groups. Users are impacted if they rely on `_uid` as a privilege boundary when launching commands from a privileged parent process.\n\n### Patches\nUpgrade to version \u003e= 2.2.4\n\n### Workarounds\nAvoid using `_uid` when the user represents a less-privileged user.",
  "id": "GHSA-q38v-wp89-2w55",
  "modified": "2026-07-17T18:41:38Z",
  "published": "2026-07-17T18:41:38Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/amoffat/sh/security/advisories/GHSA-q38v-wp89-2w55"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/amoffat/sh"
    },
    {
      "type": "WEB",
      "url": "https://github.com/amoffat/sh/releases/tag/2.2.4"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "sh _uid does not drop supplementary groups (incomplete privilege drop)"
}



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