CVE-2026-14340
MediumCVSS 5.3Exploitation Probability (EPSS)
Low risk20th percentile — higher than 20% of all known CVEs
Summary
An incorrect authorization vulnerability in GitHub Enterprise Server allowed a user-to-server token scoped to a GitHub App installation to perform write operations on public repositories outside its intended scope. The authorization check only verified read permissions on the target repository, not explicit access.
Risk Assessment
An attacker with a victim's token can create issues, comments, and private vulnerability reports on any public repository, impersonating the victim without any indication of app involvement.
Recommendation
Immediately upgrade GitHub Enterprise Server to version 3.21.2, 3.20.4, 3.19.8, 3.18.11, 3.17.17, or 3.16.20 depending on your release line.
Original NVD description (English source)
An incorrect authorization vulnerability was identified in GitHub Enterprise Server that allowed a user-to-server token scoped to a GitHub App installation to perform certain write operations on public repositories outside the token's intended scope. This was possible because the authorization check only verified that the installation had read permissions on the target repository rather than verifying that the token's installation was explicitly granted access to that repository. An attacker who obtained a victim's user-to-server token could create issues, issue comments, commit comments, and private vulnerability reports on any public repository, appearing as the victim user with no indication of the app involvement. This vulnerability was fixed by adding a repository scope check for user-to-server tokens issued by global apps. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.22 and was fixed in versions 3.21.2, 3.20.4, 3.19.8, 3.18.11, 3.17.17, 3.16.20. This vulnerability was reported via the GitHub Bug Bounty program.