CVE-2026-75834: Grav: Single invalid UTF-8 byte disables every rule in Security::detectXss(), bypassing the page-content XSS safety gate

September 17, 2026

Type: Stored XSS (CWE-79)
Auth required: Page-edit (“publisher”) account, not super-admin
Consequence: Arbitrary JavaScript execution in any visitor’s browser, including a super-admin who views the page — a cross-trust-boundary escalation from publisher to admin-equivalent action capability.

References

github.com/advisories/GHSA-q2j8-x8hf-63ch
github.com/getgrav/grav/security/advisories/GHSA-q2j8-x8hf-63ch
nvd.nist.gov/vuln/detail/CVE-2026-75834
www.vulncheck.com/advisories/grav-before-stored-xss-via-invalid-utf-8-byte

Code Behaviors & Features

Detect and mitigate CVE-2026-75834 with GitLab Dependency Scanning

Secure your software supply chain by verifying that all open source dependencies used in your projects contain no disclosed vulnerabilities. Dependency Scanning using SBOM also detects vulnerabilities from proprietary advisories that this site does not include. Learn more about Dependency Scanning using SBOM →