CVE-2026-75834 PUBLISHED

Grav before 2.0.14 Stored XSS via Invalid UTF-8 Byte

Assigner: VulnCheck
Reserved: 18.08.2026 Published: 18.08.2026 Updated: 18.08.2026

Grav before 2.0.14 contains a stored cross-site scripting vulnerability in the Security::detectXss() function (system/src/Grav/Common/Security.php). All XSS detection patterns use the PCRE /u (UTF-8) modifier, so a single invalid UTF-8 byte anywhere in page content causes preg_match() to return false for every pattern, silently bypassing the save-time XSS safety gate (Validation::checkSafety()). An authenticated attacker with page-edit permissions (without the security.xss_whitelist privilege) can store malicious JavaScript that executes in the browser of a visitor who views the affected page.

Metrics

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
CVSS Score: 5.1

Product Status

Vendor getgrav
Product grav
Versions Default: unaffected
  • affected from 0 to 2.0.14 (excl.)
  • Version 2.0.14 is unaffected

Credits

  • iaohkut-from-NightWolf-Team reporter

References

Problem Types

  • Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') CWE