What’s Vulnerable › Vulnerabilities

CVE-2026-54552: sh _uid does not drop supplementary groups (incomplete privilege drop)

• Severity: high (CVSS 7.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-18 · updated 2026-10-22
• Weakness: CWE-273

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.

Affected products

• amoffat sh: before 2.2.4

References

• https://github.com/amoffat/sh/commit/3d855daba91f87a089b490c0d1cf1df3faace2f1
• https://github.com/amoffat/sh/pull/776
• https://github.com/amoffat/sh/releases/tag/2.2.4
• https://github.com/amoffat/sh/security/advisories/GHSA-q38v-wp89-2w55

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