CVE-2026-8034 Server-side request forgery vulnerability in GitHub Enterprise Server notebook viewer via URL parser confusion
An attacker can access internal services via SSRF in the notebook viewer due to URL parser confusion, requiring network access to the server.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-8034?
CVE-2026-8034 is a high-severity server-side request forgery vulnerability in Github Enterprise Server, published on 7 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Which versions are affected by CVE-2026-8034?
It affects 1 product.
Products include Github Enterprise Server.
How do I fix CVE-2026-8034?
No fix has been published for CVE-2026-8034 yet. Limit exposure of the affected software until one is available.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-8034 being exploited?
There is no known exploitation of CVE-2026-8034 in the wild and no public exploit code.
Other vulnerabilities in Github Enterprise Server
- CVE-2024-4985 Auth bypass in Enterprise Server
- CVE-2022-23739 Missing authorization in GitHub Enterprise Server
- CVE-2022-46255 Improper Limitation of a Pathname to a Restricted Directory in GitHub Enterprise Server leading to RCE
- CVE-2021-22869 Improper access control in GitHub Enterprise Server allows self-hosted runners to execute outside their control group
- CVE-2024-9487 Auth bypass in Enterprise Server
Sources
Also known as GHSA-w548-vv26-rff6.