CVE-2023-1555: Missing 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: 2023-09-01 · updated 2026-06-17
Weakness: CWE-262

Description

An issue has been discovered in GitLab affecting all versions starting from 15.2 before 16.1.5, all versions starting from 16.2 before 16.2.5, all versions starting from 16.3 before 16.3.1. A namespace-level banned user can access the API.

Affected products

GitLab: from 15.2.0 before 16.1.5; from 16.2 before 16.2.5; 16.3.0 — fixed in 16.1.5, 16.2.5

How to fix

Upgrade to a fixed version: GitLab 16.1.5, 16.2.5. Check the vendor advisory for mitigations.

References

https://gitlab.com/gitlab-org/gitlab/-/issues/398587
https://hackerone.com/reports/1911908
https://gitlab.com/gitlab-org/gitlab/-/issues/398587
https://hackerone.com/reports/1911908

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