{"id":"CVE-2026-25121","aliases":["GHSA-5g94-c2wx-8pxw","GO-2026-4405"],"title":"apko has a path traversal in apko dirFS which allows filesystem writes outside base","summary":"apko has a path traversal in apko dirFS which allows filesystem writes outside base","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","vendor":"apko","product":"chainguard.dev/apko","ecosystem":"go","affected":["chainguard.dev/apko >= 0.14.8, < 1.1.0"],"patched":["chainguard.dev/apko 1.1.0"],"published":"2026-02-03","updated":"2026-09-10","sourceUpdated":"2026-09-10T03:50:34.269342712Z","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-5g94-c2wx-8pxw","references":[{"url":"https://github.com/chainguard-dev/apko/security/advisories/GHSA-5g94-c2wx-8pxw"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-25121"},{"url":"https://github.com/chainguard-dev/apko/commit/d8b7887a968a527791b3c591ae83928cb49a9f14"},{"url":"https://github.com/chainguard-dev/apko"}],"tags":["osv","go"],"epss":0.00384,"epssPercentile":0.32299,"ingestedAt":"2026-09-12T03:13:01.755Z","slug":"CVE-2026-25121","body":"## Overview\n\nA 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.\n\n**Fix:** Fixed by [d8b7887](https://github.com/chainguard-dev/apko/commit/d8b7887a968a527791b3c591ae83928cb49a9f14). Merged into release. \n\n**Acknowledgements**                                                                                                                                                                        \n                                                                                                                                                                                              \napko thanks Oleh Konko from [1seal](https://1seal.org/) for discovering and reporting this issue.\n\n## Affected packages\n\n- `chainguard.dev/apko >= 0.14.8, < 1.1.0`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `chainguard.dev/apko 1.1.0`","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}