CVE-2026-75101: Authorization bypass vulnerability in GitHub Enterprise Server allowed reading of private pull request diffs and patches via repository name collision

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-22 · updated 2026-10-02
Weakness: CWE-639

Description

An authorization bypass vulnerability was identified in GitHub Enterprise Server that allowed any authenticated user of the instance to read the raw diff or patch of pull requests in private repositories without authorization. Access tokens for raw pull request diffs and patches were scoped to the repository name and pull request number rather than to a globally unique repository identifier, so an attacker who created a repository and pull request matching a target's repository name and pull request number could use a token for their own repository to retrieve the private pull request's contents. Exploitation required the attacker to know the target repository's name and a valid pull request number. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.22 and was fixed in versions 3.17.21, 3.18.15, 3.19.12, 3.20.8, and 3.21.6. This vulnerability was reported via the GitHub Bug Bounty program.

Affected products

GitHub Enterprise Server: from 3.17.0 before 3.17.21; from 3.18.0 before 3.18.15; from 3.19.0 before 3.19.12; from 3.20.0 before 3.20.8; from 3.21.0 before 3.21.6 — fixed in 3.17.21, 3.18.15, 3.19.12, 3.20.8, 3.21.6

How to fix

Upgrade to a fixed version: GitHub Enterprise Server 3.17.21, 3.18.15, 3.19.12, 3.20.8. Check the vendor advisory for mitigations.

References

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