CVE-2026-8034 : faille critique github enterprise server (CVSS 9.8)

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.

Sévérité

Critique (CVSS 9.8)

Vecteur CVSS

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation active

Non signalée par la CISA

Publication

7 mai 2026

Dernière mise à jour

17 juin 2026

• github enterprise server

• Fiche CVE-2026-8034 sur le NVD (NIST)
• docs.github.com/en/[email protected]/admin/release-notes
• docs.github.com/en/[email protected]/admin/release-notes
• docs.github.com/en/[email protected]/admin/release-notes
• docs.github.com/en/[email protected]/admin/release-notes
• docs.github.com/en/[email protected]/admin/release-notes