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Description

GitLab has remediated an issue in GitLab CE/EE affecting all versions from 18.3 before 18.4.5, 18.5 before 18.5.3, and 18.6 before 18.6.1 that under specific conditions could have allowed an unauthenticated user to join arbitrary organizations by changing headers on some requests.

PUBLISHED Reserved 2025-11-03 | Published 2025-11-26 | Updated 2025-11-28 | Assigner GitLab




MEDIUM: 6.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Problem types

CWE-290: Authentication Bypass by Spoofing

Product status

Default status
unaffected

18.3 (semver) before 18.4.5
affected

18.5 (semver) before 18.5.3
affected

18.6 (semver) before 18.6.1
affected

Credits

Thanks [pwnie](https://hackerone.com/pwnie) for reporting this vulnerability through our HackerOne bug bounty program finder

References

gitlab.com/gitlab-org/gitlab/-/issues/579372 (GitLab Issue #579372) issue-tracking permissions-required

hackerone.com/reports/3370245 (HackerOne Bug Bounty Report #3370245) technical-description exploit permissions-required

cve.org (CVE-2025-12653)

nvd.nist.gov (CVE-2025-12653)

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