GitHub Enterprise Server <3.21 REPO ID Discovery via API
CVE-2026-5512 Published on April 21, 2026
Improper authorization vulnerability in GitHub Enterprise Server allowed disclosure of private repository names via mobile upload policy API
An improper authorization vulnerability was identified in GitHub Enterprise Server that allowed an authenticated attacker to determine the names of private repositories by their numeric ID. The mobile upload policy API endpoint did not perform an early authorization check, and validation error messages included the full repository name for repositories the caller did not have access to. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.20.1, 3.19.5, 3.18.8, 3.17.14, 3.16.17, 3.15.21, and 3.14.26. This vulnerability was reported via the GitHub Bug Bounty program.
Vulnerability Analysis
CVE-2026-5512 is exploitable with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Type
Insertion of Sensitive Information Into Sent Data
The code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor. Sensitive information could include data that is sensitive in and of itself (such as credentials or private messages), or otherwise useful in the further exploitation of the system (such as internal file system structure).
Products Associated with CVE-2026-5512
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Affected Versions
GitHub Enterprise Server:- Version 3.14.0, <= 3.14.25 is affected.
- Version 3.15.0, <= 3.15.20 is affected.
- Version 3.16.0, <= 3.16.16 is affected.
- Version 3.17.0, <= 3.17.13 is affected.
- Version 3.18.0, <= 3.18.7 is affected.
- Version 3.19.0, <= 3.19.4 is affected.
- Version 3.20.0 and below 3.20.1 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.