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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-54552
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-18 18:18:23 UTC
Updated2026-08-18 19:16:57 UTC
Descriptionsh 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.

Risk And Classification

Primary CVSS: v3.1 7.9 HIGH from [email protected]

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

Problem Types: CWE-273 | CWE-273 CWE-273: Improper Check for Dropped Privileges

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.9HIGHCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N
3.1CNADECLARED7.9HIGHCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
High
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Amoffat Sh affected < 2.2.4 Not specified

References

ReferenceSourceLinkTags
github.com/amoffat/sh/commit/3d855daba91f87a089b490c0d1cf1df3faace2f1 [email protected] github.com
github.com/amoffat/sh/security/advisories/GHSA-q38v-wp89-2w55 [email protected] github.com
github.com/amoffat/sh/pull/776 [email protected] github.com
github.com/amoffat/sh/releases/tag/2.2.4 [email protected] github.com
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