GitLab Patches XSS and API Denial-of-Service Vulnerabilities in CE/EE
GitLab released security updates for GitLab Community Edition (CE) and Enterprise Edition (EE), shipping patched versions 18.9.2, 18.8.6, and 18.7.6 to address multiple vulnerabilities affecting self-managed deployments. The Canadian Centre for Cyber Security issued advisory AV26-222 urging organizations to review GitLab’s upstream advisory and apply the updates for any instances running versions prior to those releases.
The update fixes 15 security issues, including a high-severity XSS vulnerability (CVE-2026-1090, CVSS 8.7) in Markdown placeholder processing when the relevant feature flag is enabled, which could allow an authenticated attacker to inject malicious JavaScript into a victim’s browser. GitLab also addressed several denial-of-service conditions, including issues impacting the GraphQL API (resource exhaustion via recursion), repository archive endpoints, and JSON payload validation in the protected branches API; additional fixes include webhook-related DoS risks (e.g., CVE-2025-13690, CVE-2025-12576) and a CRLF sequence handling issue (CVE-2026-3848).
Timeline
Mar 12, 2026
Details disclosed on XSS and API DoS flaws fixed in the GitLab update
Public reporting identified the most critical issue as CVE-2026-1090, an authenticated XSS in Markdown placeholder processing, along with multiple high-severity API-related denial-of-service flaws. The reports also noted GitLab.com and GitLab Dedicated were already patched and that detailed vulnerability reports would be published 30 days after release.
Mar 11, 2026
GitLab publishes security advisory and patched CE/EE releases
On 2026-03-11, GitLab published a security advisory for GitLab Community Edition and Enterprise Edition covering 15 vulnerabilities. It released patched versions 18.9.2, 18.8.6, and 18.7.6 for affected versions prior to those releases.
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