GitHub Enterprise Server up to 3.21.3 X-GitHub-Request-Id path traversal

Summaryinfo

A vulnerability, which was classified as critical, has been found in GitHub Enterprise Server up to 3.17.18/3.18.12/3.19.9/3.20.5/3.21.3. This issue affects some unknown processing. This manipulation of the argument X-GitHub-Request-Id causes path traversal. This vulnerability is handled as CVE-2026-17556. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability has been found in GitHub Enterprise Server up to 3.17.18/3.18.12/3.19.9/3.20.5/3.21.3 and classified as critical. Affected by this vulnerability is an unknown functionality. The manipulation of the argument X-GitHub-Request-Id with an unknown input leads to a path traversal vulnerability. The CWE definition for the vulnerability is CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at docs.github.com. This vulnerability is known as CVE-2026-17556 since 07/27/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1006 for this issue.

Upgrading to version 3.17.19, 3.18.13, 3.19.10, 3.20.6 or 3.21.4 eliminates this vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Bug Tracking Software

Vendor

• GitHub

Name

• Enterprise Server

Version

• 3.17.0
• 3.17.1
• 3.17.2
• 3.17.3
• 3.17.4
• 3.17.5
• 3.17.6
• 3.17.7
• 3.17.8
• 3.17.9
• 3.17.10
• 3.17.11
• 3.17.12
• 3.17.13
• 3.17.14
• 3.17.15
• 3.17.16
• 3.17.17
• 3.17.18
• 3.18.0
• 3.18.1
• 3.18.2
• 3.18.3
• 3.18.4
• 3.18.5
• 3.18.6
• 3.18.7
• 3.18.8
• 3.18.9
• 3.18.10
• 3.18.11
• 3.18.12
• 3.19.0
• 3.19.1
• 3.19.2
• 3.19.3
• 3.19.4
• 3.19.5
• 3.19.6
• 3.19.7
• 3.19.8
• 3.19.9
• 3.20.0
• 3.20.1
• 3.20.2
• 3.20.3
• 3.20.4
• 3.20.5
• 3.21.0
• 3.21.1
• 3.21.2
• 3.21.3

License

• open-source

CPE 2.3info

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CPE 2.2info

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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