Server-side request forgery vulnerability in GitHub Enterprise Server notebook viewer via URL parser confusion
Published May 7, 2026
7.9
HIGHCVSS 4.0
EPSS 0.86%
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.
Affected products
-
- Version 3.16.0StatusaffectedConstraints<=3.16.17
- Version 3.17.0StatusaffectedConstraints<=3.17.14
- Version 3.18.0StatusaffectedConstraints<=3.18.8
- Version 3.19.0StatusaffectedConstraints<=3.19.5
- Version 3.20.0StatusaffectedConstraints<=3.20.1
- Version 3.21.0StatusunaffectedConstraints-
- Version
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| GitHub | Enterprise Server | affected |
|
- < 3.16.18
- ≥ 3.17.0 · < 3.17.15
- ≥ 3.18.0 · < 3.18.9
- ≥ 3.19.0 · < 3.19.6
- ≥ 3.20.0 · < 3.20.2
No data.
No Red Hat product state for this CVE.
No package ranges for this CVE.
Remediation
No remediation recorded yet.
References (6)
- https://docs.github.com/en/enterprise-server@3.16/admin/release-notes#3.16.18 release-notesRelease NotesVendor Advisory
- https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.15 release-notesRelease NotesVendor Advisory
- https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.9 release-notesRelease NotesVendor Advisory
- https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.6 release-notesRelease NotesVendor Advisory
- https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.2 release-notesRelease NotesVendor Advisory
- https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-28464 Advisory
| Link | Providers | Tags |
|---|---|---|
| https://docs.github.com/en/enterprise-server@3.16/admin/release-notes#3.16.18 | release-notesRelease NotesVendor Advisory | |
| https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.15 | release-notesRelease NotesVendor Advisory | |
| https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.9 | release-notesRelease NotesVendor Advisory | |
| https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.6 | release-notesRelease NotesVendor Advisory | |
| https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.2 | release-notesRelease NotesVendor Advisory | |
| https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-28464 | Advisory |
Change history (0)
No recorded changes yet.