CVE-2025-66303 Grav is vulnerable to a DOS on the admin panel
Attackers can crash the Grav admin panel by injecting malicious cron expressions into the scheduled_at parameter, requiring manual server intervention to recover.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-66303?
CVE-2025-66303 is a medium-severity denial of service vulnerability in Getgrav Grav, published on 1 Dec 2025. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
Grav is a file-based Web platform. Prior to 1.8.0-beta.27, A Denial of Service (DoS) vulnerability has been identified in Grav related to the handling of scheduled_at parameters. Specifically, the application fails to properly sanitize input for cron expressions. By manipulating the scheduled_at parameter with a malicious input, such as a single quote, the application admin panel becomes non-functional, causing significant disruptions to administrative operations. The only way to recover from this issue is to manually access the host server and modify the backup.yaml file to correct the corrupted cron expression. This vulnerability is fixed in 1.8.0-beta.27.
Weakness: CWE-400
Which versions are affected by CVE-2025-66303?
2 open source packages ship an affected version, including getgrav/grav. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
getgrav/grav Packagist | All versions | 1.8.0-beta.27 |
getgrav/grav Packagist | All versions | 1.8.0-beta.27 |
Products include Getgrav Grav.
How do I fix CVE-2025-66303?
Upgrade getgrav/grav to 1.8.0-beta.27 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-66303 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-66303 exists.
Other vulnerabilities in Getgrav Grav
- CVE-2023-34251 Grav Server Side Template Injection vulnerability
- CVE-2025-46199 Cross-site scripting in n/a
- CVE-2021-47812 GravCMS 1.10.7 - Arbitrary YAML Write/Update (Unauthenticated) (2)
- CVE-2025-66844 Grav may be vulnerable to SSRF attack via Twig Templates
- CVE-2022-2073 Code Injection in getgrav/grav
Sources
Also known as GHSA-x62q-p736-3997.