sh _uid does not drop supplementary groups (incomplete privilege drop) (CVE-2026-54552) | HOL Guard CVE

High · CVSS 7.9CVE-2026-54552GHSA-Q38V-WP89-2W55

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

Answer in brief

CVE-2026-54552 records a High severity (CVSS 7.9) vulnerability in sh _uid does not drop supplementary groups (incomplete privilege drop). The current sources do not mark it as known exploited. The current feed maps amoffat/sh (generic), sh (pip). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 18, 2026Updated Aug 18, 2026Source checked Sep 17, 2026First seen by HOL Jul 17, 2026Material review Aug 18, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.9
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

CVSS is 7.9. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps amoffat/sh (generic), sh (pip). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
amoffat/shgeneric	< 2.2.4	Not reported
shpip	<2.2.4	2.2.4

Recommended response

Check inventory. Check lockfiles and deployed manifests for amoffat/sh, sh.
Review the reported fix. Update sh to 2.2.4 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 18, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 18, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Jul 17, 2026

Sources and claim methodology

Upstream source description

sh provides Python process launching. Prior to 2.2.4, the _uid option in sh.py performs an incomplete privilege drop on Linux and Unix-like systems. When sh runs from an elevated process and launches a command with _uid set to an unprivileged user, the child changes its UID but can retain the parent process's supplementary groups because the privilege-drop sequence does not fully establish the target user's UID, primary GID, and supplementary groups. The child can therefore retain access to files or resources granted to privileged groups such as root, docker, disk, shadow, or sudo, violating the expected _uid privilege boundary. This issue is fixed in version 2.2.4.

Quoted source text, attributed separately from HOL analysis.