CVE-2023-6680: Improper Certificate Validation in GitLab

Severity: high (CVSS 8.1 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: 2023-12-15 · updated 2026-06-17
Weakness: CWE-295

Description

An improper certificate validation issue in Smartcard authentication in GitLab EE affecting all versions from 11.6 prior to 16.4.4, 16.5 prior to 16.5.4, and 16.6 prior to 16.6.2 allows an attacker to authenticate as another user given their public key if they use Smartcard authentication. Smartcard authentication is an experimental feature and has to be manually enabled by an administrator.

Affected products

GitLab: from 11.6 before 16.4.4; from 16.5 before 16.5.4; from 16.6 before 16.6.2 — fixed in 16.4.4, 16.5.4, 16.6.2

How to fix

Upgrade to a fixed version: GitLab 16.4.4, 16.5.4, 16.6.2. Check the vendor advisory for mitigations.

References

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