CVE-2023-3979: Incorrect Authorization in GitLab

Severity: medium (CVSS 4.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-09-29 · updated 2026-06-17
Weakness: CWE-863

Description

An issue has been discovered in GitLab affecting all versions starting from 10.6 before 16.2.8, all versions starting from 16.3 before 16.3.5, all versions starting from 16.4 before 16.4.1. It was possible that upstream members to collaborate with you on your branch get permission to write to the merge request’s source branch.

Affected products

GitLab: from 10.6 before 16.2.8; from 16.3.0 before 16.3.5; 16.4.0 — fixed in 16.2.8, 16.3.5

How to fix

Upgrade to a fixed version: GitLab 16.2.8, 16.3.5. Check the vendor advisory for mitigations.

References

https://gitlab.com/gitlab-org/gitlab/-/issues/419972
https://hackerone.com/reports/2082560
https://gitlab.com/gitlab-org/gitlab/-/issues/419972
https://hackerone.com/reports/2082560

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