Resource exhaustion in Grav CMS - CVE-2025-66303
Published: May 5, 2026
Vulnerability identifier: #VU130068
CSH Severity: Low
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2025-66303
CWE-ID: CWE-400
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to improper input validation in the admin panel scheduled_at parameter handling when processing crafted cron expression input. A remote privileged user can submit a specially crafted scheduled_at value to cause a denial of service.
The issue can render the admin panel non-functional, and recovery requires manual correction of the corrupted cron expression in the backup.yaml file.
Affected software
Grav CMS
How to mitigate CVE-2025-66303
Install security update from vendor's website.
Grav CMS - update to 1.8.0 beta.27