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CVE-2026-3306: Improper authorization in GitHub Projects allows modification of issue and pull request metadata without repository write access

• Severity: medium (CVSS 4.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-03-10 · updated 2026-06-17
• Weakness: CWE-639

Description

An improper authorization vulnerability was identified in GitHub Enterprise Server that allowed a user with read access to a repository and write access to a project to modify issue and pull request metadata through the project. When adding an item to a project that already existed, column value updates were applied without verifying the actor's repository write permissions. This vulnerability was reported via the GitHub Bug Bounty program and has been fixed in GitHub Enterprise Server versions 3.14.24, 3.15.19, 3.16.15, 3.17.12, 3.18.6 and 3.19.3.

Affected products

• GitHub Enterprise Server: before 3.14.24; from 3.15.0 before 3.15.19; from 3.16.0 before 3.16.15; from 3.17.0 before 3.17.12; from 3.18.0 before 3.18.6; from 3.19.0 before 3.19.3 — fixed in 3.14.24, 3.15.19, 3.16.15, 3.17.12, 3.18.6, 3.19.3

How to fix

Upgrade to a fixed version: GitHub Enterprise Server 3.14.24, 3.15.19, 3.16.15, 3.17.12. Check the vendor advisory for mitigations.

References

• https://docs.github.com/en/enterprise-server@3.14/admin/release-notes#3.14.24
• https://docs.github.com/en/enterprise-server@3.15/admin/release-notes#3.15.19
• https://docs.github.com/en/enterprise-server@3.16/admin/release-notes#3.16.15
• https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.12
• https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.6
• https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.3

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