CVE-2023-3906: Improper Validation of Specified Type of Input in GitLab

Severity: low (CVSS 3.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% 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-1287

Description

An input validation issue in the asset proxy in GitLab EE, affecting all versions from 12.3 prior to 16.2.8, 16.3 prior to 16.3.5, and 16.4 prior to 16.4.1, allowed an authenticated attacker to craft image urls which bypass the asset proxy.

Affected products

GitLab: from 12.3 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/419213
https://hackerone.com/reports/2071411
https://gitlab.com/gitlab-org/gitlab/-/issues/419213
https://hackerone.com/reports/2071411

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