Improper Verification of Cryptographic Signature Affecting kas package, versions <5.3-1

Note: Versions mentioned in the description apply only to the upstream kas package and not the kas package as distributed by Debian. See How to fix? for Debian:unstable relevant fixed versions and status.

kas is a setup tool for bitbake based projects. Prior to version 5.3, when relying solely on a git commit ID (SHA-1 or SHA-256) to qualify if a checkout of a repository is equivalent to the state validated while adding its commit ID to a kas configuration, users may be tricked to check out a branch of the same name from this repository. This implies that the referenced repository has been taken over by an attacker and modified to carry such a branch. SHA-1 commits may also be replaced by creating hash collisions, so the primary impact of this issue is on SHA-256 commit IDs. Version 5.3 fixes the issue. As a workaround, avoid relying solely on the commit ID for integrity validation of a repository that might become under control of a malicious 3rd party. If available, additional validate cryptographically signed commits or tags. Alternatively, mirror the repository to a save place, validate its integrity, and use this instead of the original one.

• https://security-tracker.debian.org/tracker/CVE-2026-47191
• https://github.com/pypa/advisory-database/tree/main/vulns/kas/PYSEC-2026-2544.yaml
• https://github.com/siemens/kas/commit/4cb4a3d01122ffaec9feaae768a5814092f6f9b5
• https://github.com/siemens/kas/security/advisories/GHSA-qjwp-hrq6-r26r