CVE-2026-17556

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.

CVSS v3 9.1 CRITICAL

9.1^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 3.9 / Impact : 5.2

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.19	Product Release Notes
https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.13	Product Release Notes
https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.10	Product Release Notes
https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.6	Product Release Notes
https://docs.github.com/en/enterprise-server@3.21/admin/release-notes#3.21.4	Product Release Notes

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:github:enterprise_server::::::::
	cpe:2.3:a:github:enterprise_server::::::::
	cpe:2.3:a:github:enterprise_server::::::::
	cpe:2.3:a:github:enterprise_server::::::::
	cpe:2.3:a:github:enterprise_server::::::::

History

No history.

Information

Published : 2026-08-05 20:17

Updated : 2026-08-18 18:08

NVD link : CVE-2026-17556

Mitre link : CVE-2026-17556

CVE.ORG link : CVE-2026-17556

JSON object : View

Products Affected

github

enterprise_server

CWE

CWE-22

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

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