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CVE-2026-8034

Server-side request forgery vulnerability in GitHub Enterprise Server notebook viewer via URL parser confusion

Published: May 7, 2026Updated: May 11, 2026 Sources: CVE List NVDCWE-436
NVD MITRE
9.8CVSSCRITICAL
EPSS Score
0.4%
Top 72.1%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:HI:HA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:HAvailability
High
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Weaknesses

CWE-436CWE-918

Affected Products

enterprise servergithubDevTools & CI
Enterprise ServerGitHubDevTools & CI
githubcommercialUSDevTools & CIaka github

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

2 techniques
Command and Control
Initial Access
View detailed technique mapping

References

https://docs.github.com/en/enterprise-server@3.16/admin/release-notes#3.16.18
docs.github.com
https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.15
docs.github.com
https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.9
docs.github.com
and 2 more references View all →

Timeline

Published
May 7, 2026
Last Updated
May 11, 2026

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