Vulnerability · Published May 7, 2026 · Assigned by GitHub_P
CVE-2026-8034Server-side request forgery vulnerability in GitHub Enterprise Server notebook viewer via URL parser confusion
High 7.9
In plain English
A high-severity server-side request forgery in Enterprise Server from GitHub. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 44% of all known vulnerabilities).
Official 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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| GitHub | Enterprise Server | 3.16.0 – through 3.16.173.17.0 – through 3.17.143.18.0 – through 3.18.83.19.0 – through 3.19.53.20.0 – through 3.20.1 |
Weakness: CWE-918, CWE-436 · 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
References
- https://docs.github.com/en/enterprise-server@3.16/admin/release-notes#3.16.18 release-notes
- https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.15 release-notes
- https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.9 release-notes
- https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.6 release-notes
- https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.2 release-notes