A server-side request forgery (SSRF) vulnerability was identified in the GitHub Enterprise Server notebook viewer that
Source GCVE Database
Not known to be exploited · CVSS 7.9 High · fixed in 3.16.18 : patch Enterprise Server soon.
Data as of 27 Oct 2026, 00:13 UTC
- Patch
- Available – fixed in 3.16.18
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:HExploitation evidence
Disclosed: evidence found.
CVE published 7 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| GitHubEnterprise Server | Affected
| Fixed in– |
AI-suggested
This vulnerability is fixed in GitHub Enterprise Server versions 3.16.18, 3.17.15, 3.18.9, 3.19.6, and 3.20.2. Users should upgrade to one of these fixed versions or later. Since this is not a cloud service, remediation requires applying these official patches. No additional mitigations are noted.
Description
A critical server-side request forgery (SSRF) vulnerability exists in the GitHub Enterprise Server notebook viewer. It arises from a discrepancy between the URL parser used for hostname validation and the HTTP request library, allowing crafted URLs to bypass validation and access unintended internal hosts. This affects all GitHub Enterprise Server versions prior to 3.21. The issue requires network access to the server instance to exploit and was fixed in versions 3.16.18, 3.17.15, 3.18.9, 3.19.6, and 3.20.2.
References
- nvd.nist.gov/vuln/detail/CVE-2026-8034 (opens in a new tab)
- docs.github.com/en/enterprise-server@3.16/admin/release-notes (opens in a new tab)
- docs.github.com/en/enterprise-server@3.17/admin/release-notes (opens in a new tab)
- docs.github.com/en/enterprise-server@3.18/admin/release-notes (opens in a new tab)
- docs.github.com/en/enterprise-server@3.19/admin/release-notes (opens in a new tab)
- docs.github.com/en/enterprise-server@3.20/admin/release-notes (opens in a new tab)