sh _uid does not drop supplementary groups (incomplete privilege drop)

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.9 · CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N

EPSS

• CVE-2026-54552: 0.17% estimated exploitation activity in the next 30 days; percentile 6.33 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.

Published by the source

17 Jul 2026, 18:41 UTC

Last modified by the source

23 Jul 2026, 15:11 UTC

Source last checked

26 Oct 2026, 13:47 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-q38v-wp89-2w55

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-q38v-wp89-2w55

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# Patch Next advisory brief: CVE-2026-54552

Advisory: sh _uid does not drop supplementary groups (incomplete privilege drop)
IDs: CVE-2026-54552, GHSA-q38v-wp89-2w55
Record: https://patchnext.com/advisories/cve-2026-54552 (revision 2, source checked 26 Oct 2026, 13:47 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: sh 2.2.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI sh: affected < 2.2.4; fixed in 2.2.4

## Suggested inspection (read-only)
- `python -m pip show sh`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on sh.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-q38v-wp89-2w55 (OSV record GHSA-q38v-wp89-2w55 lists affected ranges: PyPI sh >=0 <2.2.4 (fixed))
- Verified: https://github.com/advisories/GHSA-q38v-wp89-2w55 (GitHub-reviewed advisory GHSA-q38v-wp89-2w55 lists affected ranges: PyPI sh >=0 <2.2.4)

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