# CVE-2026-17556: Path traversal in GitHub Enterprise Server allowed unauthenticated deletion of instance storage via the X-GitHub-Request-Id header

> CVE-2026-17556: Path traversal in GitHub Enterprise Server allowed unauthenticated deletion of instance storage via the X-GitHub-Request-Id header. CVSS 9.1 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-17556
Last updated: 2026-10-23T21:10:00Z

- Published: 2026-08-05 20:05 UTC · Updated: 2026-10-23 21:10 UTC · Assigner: GitHub\_P
- CVSS: 9.1 (CVSS 3.1) · Severity: Critical · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
- EPSS: 0.81%, 56th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-22

## 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.

## Affected vendors and products

- GitHub: Enterprise Server

## Tracked companies

- [GitHub](https://rewindex.com/company/github.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-17556)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-17556)
- [https://docs.github.com/en/enterprise-server@3.17/admin/release-notes\#3.17.19](https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.19)
- [https://docs.github.com/en/enterprise-server@3.18/admin/release-notes\#3.18.13](https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.13)
- [https://docs.github.com/en/enterprise-server@3.19/admin/release-notes\#3.19.10](https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.10)
- [https://docs.github.com/en/enterprise-server@3.20/admin/release-notes\#3.20.6](https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.6)
- [https://docs.github.com/en/enterprise-server@3.21/admin/release-notes\#3.21.4](https://docs.github.com/en/enterprise-server@3.21/admin/release-notes#3.21.4)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-17556 · Markdown: https://rewindex.com/cve/CVE-2026-17556.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-17556 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:16:37.977Z