In short
- CVE-2026-25121 is a HIGH (CVSS 7.5) vulnerability affecting chainguard.dev/apko, apko (chainguard).
- Chance of exploitation in the next 30 days (EPSS): 0.41%, higher than 35.6% of all vulnerabilities.
- Fix: update to 1.1.0, 1.1.1 or later.
Description
A Path Traversal vulnerability was discovered in apko's dirFS filesystem abstraction. An attacker who can supply a malicious APK package (e.g., via a compromised or typosquatted repository) could create directories or symlinks outside the intended installation root. The MkdirAll, Mkdir, and Symlink methods in pkg/apk/fs/rwosfs.go use filepath.Join() without validating that the resulting path stays within the base directory.
Fix: Fixed by d8b7887. Merged into release.
Acknowledgements
apko thanks Oleh Konko from 1seal for discovering and reporting this issue.
NVD description
apko allows users to build and publish OCI container images built from apk packages. From version 0.14.8 to before 1.1.1, a path traversal vulnerability was discovered in apko's dirFS filesystem abstraction. An attacker who can supply a malicious APK package (e.g., via a compromised or typosquatted repository) could create directories or symlinks outside the intended installation root. The MkdirAll, Mkdir, and Symlink methods in pkg/apk/fs/rwosfs.go use filepath.Join() without validating that the resulting path stays within the base directory. This issue has been patched in version 1.1.1.
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