Grav Cron Expression Handling Denial-of-Service Vulnerability

A denial-of-service vulnerability has been identified in Grav versions prior to 1.8.0-beta.27. The issue arises from the application's improper sanitization of cron expression inputs within the 'scheduled_at' parameter. This flaw can be exploited by injecting malicious inputs, such as a single quote, which disrupts the functionality of the application admin panel. As a result, administrative operations are significantly hampered. To resolve this issue, users must manually access the host server and edit the 'backup.yaml' file to restore the correct cron expression.

Impact

Exploitation of this vulnerability causes the admin panel to malfunction, leading to considerable disruptions in administrative tasks.

Reproduction

To reproduce this vulnerability, navigate to the 'http://127.0.0.1/admin/tools' endpoint and change the 'scheduled_at' parameter value to a single quote. This input will corrupt the cron expression, causing the admin panel to break. The 'backup.yaml' file will reflect this change, indicating the corrupted cron expression.

Remediation

Users can update to Grav version 1.8.0-beta.27 or later, where this vulnerability has been fixed.