GitHub Enterprise Server up to 3.20.x URL Parser server-side request forgery

Summaryinfo

A vulnerability has been found in GitHub Enterprise Server up to 3.20.x and classified as critical. The impacted element is an unknown function of the component URL Parser. The manipulation leads to server-side request forgery. This vulnerability is listed as CVE-2026-8034. The attack may be initiated remotely. There is no available exploit. The affected component should be upgraded.

Detailsinfo

A vulnerability, which was classified as critical, has been found in GitHub Enterprise Server up to 3.20.x. This issue affects an unknown part of the component URL Parser. The manipulation with an unknown input leads to a server-side request forgery vulnerability. Using CWE to declare the problem leads to 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. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

The weakness was presented by R31n. The advisory is shared at docs.github.com. The identification of this vulnerability is CVE-2026-8034 since 05/06/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Neither technical details nor an exploit are publicly available.

Upgrading to version 3.21.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-1432). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

• Microsoft GitHub Enterprise

Productinfo

Type

• Bug Tracking Software

Vendor

• GitHub

Name

• Enterprise Server

Version

• 3.0
• 3.1
• 3.2
• 3.3
• 3.4
• 3.5
• 3.6
• 3.7
• 3.8
• 3.9
• 3.10
• 3.11
• 3.12
• 3.13
• 3.14
• 3.15
• 3.16
• 3.16.0
• 3.16.1
• 3.16.2
• 3.16.3
• 3.16.4
• 3.16.5
• 3.16.6
• 3.16.7
• 3.16.8
• 3.16.9
• 3.16.10
• 3.16.11
• 3.16.12
• 3.16.13
• 3.16.14
• 3.16.15
• 3.16.16
• 3.16.17
• 3.17
• 3.17.0
• 3.17.1
• 3.17.2
• 3.17.3
• 3.17.4
• 3.17.5
• 3.17.6
• 3.17.7
• 3.17.8
• 3.17.9
• 3.17.10
• 3.17.11
• 3.17.12
• 3.17.13
• 3.17.14
• 3.18
• 3.18.0
• 3.18.1
• 3.18.2
• 3.18.3
• 3.18.4
• 3.18.5
• 3.18.6
• 3.18.7
• 3.18.8
• 3.19
• 3.19.0
• 3.19.1
• 3.19.2
• 3.19.3
• 3.19.4
• 3.19.5
• 3.20
• 3.20.0
• 3.20.1

License

• open-source

CPE 2.3info

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CPE 2.2info

• 🔒
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Entryinfo

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