Vulnerability Description
A path traversal vulnerability was identified in GitHub Enterprise Server that allowed an unauthenticated attacker to delete arbitrary files and directories on the instance, including the entire user storage directory containing Git LFS objects, release assets, attachments, and avatars. The X-GitHub-Request-Id request header was used without sanitization as a filesystem path segment for the upload buffer directory, so a traversal value pointed the buffer at an arbitrary path and the deferred cleanup routine recursively removed the traversed target. Exploitation required only network reachability to the instance and no authentication, and it worked even when private mode was enabled. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.22 and was fixed in versions 3.21.4, 3.20.6, 3.19.10, 3.18.13 and 3.17.19. This vulnerability was reported via the GitHub Bug Bounty program.
Related Weaknesses (CWE)
References
- https://docs.github.com/en/[email protected]/admin/release-notes#3.17.19
- https://docs.github.com/en/[email protected]/admin/release-notes#3.18.13
- https://docs.github.com/en/[email protected]/admin/release-notes#3.19.10
- https://docs.github.com/en/[email protected]/admin/release-notes#3.20.6
- https://docs.github.com/en/[email protected]/admin/release-notes#3.21.4
FAQ
What is CVE-2026-17556?
CVE-2026-17556 is a documented vulnerability. A path traversal vulnerability was identified in GitHub Enterprise Server that allowed an unauthenticated attacker to delete arbitrary files and directories on the instance, including the entire user ...
How severe is CVE-2026-17556?
CVSS scoring is not yet available for CVE-2026-17556. Check NVD for updates.
Is there a patch for CVE-2026-17556?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.