CVE-2023-5356: Incorrect Authorization in GitLab

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-01-12 · updated 2026-06-17
Weakness: CWE-863

Description

Incorrect authorization checks in GitLab CE/EE from all versions starting from 8.13 before 16.5.6, all versions starting from 16.6 before 16.6.4, all versions starting from 16.7 before 16.7.2, allows a user to abuse slack/mattermost integrations to execute slash commands as another user.

Affected products

GitLab: from 8.13.0 before 16.5.6; from 16.6.0 before 16.6.4; 16.7.0, 16.7.1 — fixed in 16.5.6, 16.6.4

How to fix

Upgrade to a fixed version: GitLab 16.5.6, 16.6.4. Check the vendor advisory for mitigations.

References

https://gitlab.com/gitlab-org/gitlab/-/issues/427154
https://hackerone.com/reports/2188868
https://gitlab.com/gitlab-org/gitlab/-/issues/427154
https://hackerone.com/reports/2188868

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