by Kastro
Paper/Archive/CVE-2026-8034

CVE-2026-8034

GitHub Enterprise Server — Server-side request forgery vulnerability in GitHub Enterprise Server notebook viewer via URL parser confusion

EPSS 0.5%CVSS 9.8
critical.is priorityof 100
38
CVSS 9.8 (NVD)9.8 / 10 × 3029.4Not in CISA KEV+300.0EPSS percentile 44.1.441 × 208.8No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
Enterprise Server3.16.0 – 3.16.173.21.0CNA
Enterprise Server3.17.0 – 3.17.143.21.0CNA
Enterprise Server3.18.0 – 3.18.83.21.0CNA
Enterprise Server3.19.0 – 3.19.53.21.0CNA
Enterprise Server3.20.0 – 3.20.13.21.0CNA

Scores by source

NVD9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
GitHub_P (CNA)7.9CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H
CISA ADPSSVCExploitation: none · Automatable: no · Technical impact: partial

References

refdocs.github.com/en/[email protected]/admin/release-notes#3.16.18refdocs.github.com/en/[email protected]/admin/release-notes#3.17.15refdocs.github.com/en/[email protected]/admin/release-notes#3.18.9refdocs.github.com/en/[email protected]/admin/release-notes#3.19.6refdocs.github.com/en/[email protected]/admin/release-notes#3.20.2