CVE-2026-8034

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. Limited direct impact.

Exploit odds

0.5% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-05-07 22:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-26 20:10 UTC Last updatedMost recent change to the record

Details

Published

2026-05-07 22:16 UTC

Last modified

2026-10-26 20:10 UTC

Exploit probability

0.5% · EPSS, next 30 days

Weakness

CWE-436

Record status

Analyzed

Affected

• GitHub Enterprise Server < 3.16.18
• GitHub Enterprise Server < 3.17.15
• GitHub Enterprise Server < 3.18.9
• GitHub Enterprise Server < 3.19.6
• GitHub Enterprise Server < 3.20.2

Attack profile CVSS 4.0 · 7.9

Attack vector

Network

Complexity

Low

Attack requirements

None

Privileges needed

None

User interaction

None

Confidentiality

None

Integrity

None

Availability

None