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

medium Affects getgrav/grav. Feed 2026.10.29.1, updated 2026-10-28; published 2026-09-17.

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

Package: getgrav/grav Composer
Affected versions: <2.0.14
Fixed in: 2.0.14
Severity: medium CVSS 5.4
Exploitation: not on CISA KEV · EPSS 0% (17.0th percentile)
Published: 2026-09-17
Source: osv.dev

References

Am I affected?

Find out in one command. phpwarden checks your composer.lock against this advisory and 20,000+ others, ranked by real-world exploitation (CISA KEV + EPSS). Free, offline, open data.

# one-time install
pip install phpwarden

# then
phpwarden deps composer.lock

Or keep it checked automatically: GitHub Action · pre-commit hook · GitLab CI · Laravel artisan command

Install docs How findings are ranked

Related advisories

CVE-2024-27921 high Grav File Upload Path Traversal same package: getgrav/grav
CVE-2021-29440 high Grav's Twig processing allowing dangerous PHP functions by default same package: getgrav/grav
CVE-2022-2073 high Code injection in grav same package: getgrav/grav
CVE-2020-11529 medium Open Redirect in Grav same package: getgrav/grav
CVE-2024-28116 high Server-Side Template Injection (SSTI) with Grav CMS security sandbox bypass same package: getgrav/grav
CVE-2026-61450 medium Grav: Twig sandbox config exfiltration via grav.offsetGet + dump filter (CVE-2026-44738 by same package: getgrav/grav