CVE-2026-8034
Undergoing Analysis Undergoing Analysis - In Progress
SSRF in GitHub Enterprise Server Notebook Viewer

Publication date: 2026-05-07

Last updated on: 2026-05-07

Assigner: GitHub, Inc. (Products Only)

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.
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Meta Information
Published
2026-05-07
Last Modified
2026-05-07
Generated
2026-05-09
AI Q&A
2026-05-08
EPSS Evaluated
N/A
NVD
EUVD
Affected Vendors & Products
Showing 6 associated CPEs
Vendor Product Version / Range
github enterprise_server to 3.21 (exc)
github enterprise_server 3.16.18
github enterprise_server 3.17.15
github enterprise_server 3.18.9
github enterprise_server 3.19.6
github enterprise_server 3.20.2
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-436 Product A handles inputs or steps differently than Product B, which causes A to perform incorrect actions based on its perception of B's state.
CWE-918 The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability is a server-side request forgery (SSRF) issue found in the GitHub Enterprise Server notebook viewer. It occurs because the URL validation process uses a different URL parser than the HTTP request library. This mismatch allows an attacker to craft a URL that passes validation but causes the server to send a request to an unintended internal host. Exploiting this requires the attacker to have network access to the GitHub Enterprise Server instance.


How can this vulnerability impact me? :

The impact of this vulnerability is that an attacker could use it to access internal services that are normally not exposed externally. This could lead to unauthorized access to sensitive internal resources or data, potentially compromising the security of the affected GitHub Enterprise Server environment.


What immediate steps should I take to mitigate this vulnerability?

To mitigate this vulnerability, you should upgrade your GitHub Enterprise Server to one of the fixed versions: 3.16.18, 3.17.15, 3.18.9, 3.19.6, or 3.20.2 or later.

Since exploitation requires network access to the GitHub Enterprise Server instance, restricting network access to trusted users and networks can also help reduce risk.


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