CVE-2026-1456
Published: 11 February 2026
Summary
CVE-2026-1456 is a medium-severity Allocation of Resources Without Limits or Throttling (CWE-770) vulnerability in Gitlab Gitlab. Its CVSS base score is 6.5 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application Exhaustion Flood (T1499.003); ranked at the 11.8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SC-5 (Denial-of-service Protection) and SI-10 (Information Input Validation).
Deeper analysis
CVE-2026-1456 is a denial-of-service vulnerability in GitLab Community Edition (CE) and Enterprise Edition (EE), affecting all versions from 18.7 prior to 18.7.4 and from 18.8 prior to 18.8.4. The flaw enables CPU exhaustion through exponential processing triggered by specially crafted Markdown files submitted to the Markdown preview feature. It carries a CVSS v3.1 base score of 6.5 (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) and maps to CWE-770 (Allocation of Resources Without Limits or Throttling).
An unauthenticated user, as described in the advisory, can exploit the vulnerability by submitting malicious Markdown files, causing significant CPU resource consumption and disrupting service availability. While the CVSS vector indicates low privileges (PR:L) are required, the impact is confined to high availability disruption with no effects on confidentiality or integrity.
GitLab has remediated the issue via patch releases, including GitLab 18.8.4, as outlined in their release notes at https://about.gitlab.com/releases/2026/02/10/patch-release-gitlab-18-8-4-released/. Administrators should upgrade affected instances to GitLab 18.7.4 or later, or 18.8.4 or later. Further technical details are available in the GitLab issue tracker at https://gitlab.com/gitlab-org/gitlab/-/issues/587688 and the HackerOne disclosure report at https://hackerone.com/reports/3517928.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-7048
Vulnerability details
GitLab has remediated an issue in GitLab CE/EE affecting all versions from 18.7 before 18.7.4, and 18.8 before 18.8.4 that could have allowed an unauthenticated user to cause denial of service through CPU exhaustion by submitting specially crafted markdown files…
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that trigger exponential processing in markdown preview.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Markdown preview input processing flaw directly enables application-layer resource exhaustion (CPU) DoS.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly implements protections against resource-exhaustion DoS attacks triggered by crafted Markdown input to the preview endpoint.
Requires validation and sanitization of Markdown input to reject or safely handle payloads that trigger exponential CPU processing.
Limits allocation of processing resources so that a single Markdown preview request cannot exhaust CPU capacity.