Headline
GHSA-5662-cv6m-63wh: melange's world-writable permissions expose SBOM files to potential image tampering
It was discovered that the SBOM files generated by melange in apks had file system permissions mode 666:
$ apkrane ls https://packages.wolfi.dev/os/x86_64/APKINDEX.tar.gz -P hello-wolfi --full --latest | xargs wget -q -O - | tar tzv 2>/dev/null var/lib/db/sbom
drwxr-xr-x root/root 0 2025-06-23 14:17 var/lib/db/sbom
-rw-rw-rw- root/root 3383 2025-06-23 14:17 var/lib/db/sbom/hello-wolfi-2.12.2-r1.spdx.json
This issue was introduced in commit 1b272db ("Persist workspace filesystem throughout package builds (#1836)") (v0.23.0).
Impact
This potentially allows an unprivileged user to tamper with apk SBOMs on a running image, potentially confusing security scanners. An attacker could also perform a DoS under special circumstances.
Patches
This issue was addressed in melange in e29494b ("fix: tighten up permissions for written SBOM files and signature tarballs (#2086)") (v0.29.5).
Acknowledgements
Thanks to Cody Harris H2O.ai and Markus Boehme for independently reporting this issue.
Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.