A server-side request forgery (SSRF) vulnerability was identified in the GitHub Enterprise Server notebook viewer that allowed an attacker to access internal services by exploiting URL parser confusion between the validation layer and the HTTP request library. The hostname validation used a different URL parser than the request library, enabling a crafted URL to pass validation while directing the request to an unintended host. Exploitation required network access to the GitHub Enterprise Server instance. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.16.18, 3.17.15, 3.18.9, 3.19.6, and 3.20.2. This vulnerability was reported via the GitHub Bug Bounty program.
History

Thu, 07 May 2026 22:45:00 +0000

Type Values Removed Values Added
First Time appeared Github
Github enterprise Server
Vendors & Products Github
Github enterprise Server

Thu, 07 May 2026 21:45:00 +0000

Type Values Removed Values Added
Description A server-side request forgery (SSRF) vulnerability was identified in the GitHub Enterprise Server notebook viewer that allowed an attacker to access internal services by exploiting URL parser confusion between the validation layer and the HTTP request library. The hostname validation used a different URL parser than the request library, enabling a crafted URL to pass validation while directing the request to an unintended host. Exploitation required network access to the GitHub Enterprise Server instance. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.16.18, 3.17.15, 3.18.9, 3.19.6, and 3.20.2. This vulnerability was reported via the GitHub Bug Bounty program.
Title Server-side request forgery vulnerability in GitHub Enterprise Server notebook viewer via URL parser confusion
Weaknesses CWE-436
CWE-918
References
Metrics cvssV4_0

{'score': 7.9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_P

Published:

Updated: 2026-05-07T21:18:49.812Z

Reserved: 2026-05-06T13:06:48.690Z

Link: CVE-2026-8034

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-05-07T22:16:37.230

Modified: 2026-05-07T22:16:37.230

Link: CVE-2026-8034

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-07T22:30:36Z