Path traversal in GitHub Enterprise Server
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- None · High · High
- Fix status
- No fix listed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| GitHub | Enterprise Server | 3.17.0 – 3.17.18; 3.18.0 – 3.18.12; 3.19.0 – 3.19.9; 3.20.0 – 3.20.5; 3.21.0 – 3.21.3 | — | No fix listed | CNA |
- Enterprise Server VendorGitHub Affected 3.17.0 – 3.17.18; 3.18.0 – 3.18.12; 3.19.0 – 3.19.9; 3.20.0 – 3.20.5; 3.21.0 – 3.21.3 Fixed in — No fix listed CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:* | before 3.17.19; 3.18.0 to before 3.18.13; 3.19.0 to before 3.19.10; 3.20.0 to before 3.20.6; 3.21.0 to before 3.21.4 | Vulnerable | GitHub |
- cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:* Versions before 3.17.19; 3.18.0 to before 3.18.13; 3.19.0 to before 3.19.10; 3.20.0 to before 3.20.6; 3.21.0 to before 3.21.4 Vulnerable ·GitHub
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2026-17556
- 2026-10-03 Alias added: GHSA-h3g3-4265-wv56
References
Other 5
- 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
More GitHub Enterprise Server vulnerabilities
- TI-2024-04632 An authentication bypass vulnerability was present in the GitHub Enterprise Server (GHES)… CVSS 4.0CRITICAL 10.0
- TI-2024-00181 Unsafe Reflection in Github Enterprise Server leading to Command Injection CVSS 3.1CRITICAL 9.8
- TI-2024-00466 Privilege Escalation by Code Injection in the Management Console in GitHub Enterprise Server CVSS 3.1HIGH 8.8
- TI-2026-03340 Remote code execution via git push option injection in GitHub Enterprise Server CVSS 4.0HIGH 8.7
- TI-2024-08804 Improper signature verification in GitHub Enterprise Server CVSS 4.0CRITICAL 9.5
- TI-2026-08177 Server-side request forgery in GitHub Enterprise Server CVSS 4.0CRITICAL 9.2
Sources
- CVE-2026-17556 · CVE Program
- CVE-2026-17556 · NVD
- FIRST EPSS
- GHSA-h3g3-4265-wv56 · GitHub Advisory Database · CC BY 4.0
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