CVE-2026-8034
Server-side request forgery vulnerability in GitHub Enterprise Server notebook viewer via URL parser confusion
- 7.9HighCVSS base score
- 0.52%Exploitation in 30 daysEPSS · top 55% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By GitHub_P
- 1 day later
· 1 day later
Published
- 1 day later
· 1 day later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_PCNA (assigner) | 4.0 | High7.9 | 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 |
| NVDNVD · Analyzed | 4.0 | High7.9 | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
- EPSS (exploitation in 30 days)
- 0.52% · top 55% of all CVEs (11 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.9.
Affected products
- affected 3.16.0 – ≤ 3.16.17
- affected 3.17.0 – ≤ 3.17.14
- affected 3.18.0 – ≤ 3.18.8
- affected 3.19.0 – ≤ 3.19.5
- affected 3.20.0 – ≤ 3.20.1
- unaffected 3.21.0
References
References5
- https://docs.github.com/en/[email protected]/admin/release-notes#3.16.18 (opens in a new tab)release-notes
- https://docs.github.com/en/[email protected]/admin/release-notes#3.17.15 (opens in a new tab)release-notes
- https://docs.github.com/en/[email protected]/admin/release-notes#3.18.9 (opens in a new tab)release-notes
- https://docs.github.com/en/[email protected]/admin/release-notes#3.19.6 (opens in a new tab)release-notes
- https://docs.github.com/en/[email protected]/admin/release-notes#3.20.2 (opens in a new tab)release-notes
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-28464 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-8034)Record last updated .