CVE-2026-8034
criticalpriority · track · 39EPSS 0.005 · 44 %ileDEEUUSEPSS · scored 2026-10-27
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.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–critical · 5–9.8
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (21)
Products and version ranges known to be affected.
advisories (1)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2026-1432Microsoft GitHub Enterprise: Mehrere SchwachstellenDeutsch2026-05-07csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Microsoft GitHub Enterprise ausnutzen, um Sicherheitsvorkehrungen zu umgehen, um einen Denial of Service Angriff durchzuführen, und um Informationen offenzulegen.
also known as (3)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (11)
External citations — patches, advisories, analysis.
- https://nvd.nist.gov/vuln/detail/CVE-2026-8034cnnvd
- https://docs.github.com/en/enterprise-server@3.16/admin/release-notes#3.16.18enisa_euvd
- https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.15enisa_euvd
- https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.9enisa_euvd
- https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.6enisa_euvd
- https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.2enisa_euvd
- https://docs.github.com/en/enterprise-server@3.16/admin/release-notes#3.16.18Release NotesVendor Advisorynvd
- https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.15Release NotesVendor Advisorynvd
Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.
Free scan