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Description

GitLab has remediated an issue in GitLab CE/EE affecting all versions from 9.2 before 18.7.5, 18.8 before 18.8.5, and 18.9 before 18.9.1 that could have allowed an unauthenticated user to cause regular expression denial of service by sending specially crafted input to a merge request endpoint under certain conditions.

PUBLISHED Reserved 2026-01-23 | Published 2026-02-25 | Updated 2026-02-26 | Assigner GitLab




HIGH: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem types

CWE-1333: Inefficient Regular Expression Complexity

Product status

Default status
unaffected

9.2 (semver) before 18.7.5
affected

18.8 (semver) before 18.8.5
affected

18.9 (semver) before 18.9.1
affected

Credits

Thanks [sim4n6](https://hackerone.com/sim4n6) for reporting this vulnerability through our HackerOne bug bounty program finder

References

gitlab.com/gitlab-org/gitlab/-/issues/587560 (GitLab Issue #587560) issue-tracking permissions-required

hackerone.com/reports/3482893 (HackerOne Bug Bounty Report #3482893) technical-description exploit permissions-required

about.gitlab.com/...25/patch-release-gitlab-18-9-1-released/

cve.org (CVE-2026-1388)

nvd.nist.gov (CVE-2026-1388)

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