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CVE-2026-3307: Authorization bypass in GitHub Enterprise Server secret scanning push protection allows cross-repository modification of delegated bypass reviewers

• Severity: low (CVSS 2.7 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: 2026-04-21 · updated 2026-10-26
• Weakness: CWE-639

Description

An authorization bypass vulnerability was identified in GitHub Enterprise Server that allowed an attacker with admin access on one repository to modify the secret scanning push protection delegated bypass reviewer list on another repository by manipulating the owner_id parameter in the request body. Authorization was verified against the repository in the URL, but the action was applied to a different repository specified in the request body. The impact is limited to assigning existing trusted users as bypass reviewers; it does not allow adding arbitrary external users. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.14.25, 3.15.20, 3.16.16, 3.17.13, 3.18.7, 3.19.4 and 3.20.1. This vulnerability was reported via the GitHub Bug Bounty program.

Affected products

• GitHub Enterprise Server: before 3.14.26; from 3.15.0 before 3.15.21; from 3.16.0 before 3.16.17; from 3.17.0 before 3.17.14; from 3.18.0 before 3.18.8; from 3.19.0 before 3.19.5 — fixed in 3.14.26, 3.15.21, 3.16.17, 3.17.14, 3.18.8, 3.19.5

How to fix

Upgrade to a fixed version: GitHub Enterprise Server 3.14.26, 3.15.21, 3.16.17, 3.17.14. Check the vendor advisory for mitigations.

References

• https://docs.github.com/en/enterprise-server@3.14/admin/release-notes#3.14.25
• https://docs.github.com/en/enterprise-server@3.15/admin/release-notes#3.15.20
• https://docs.github.com/en/enterprise-server@3.16/admin/release-notes#3.16.16
• https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.13
• https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.7
• https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.4
• https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.1

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