CVE-2025-66303: Grav is vulnerable to a DOS on the admin panel

DOS on the admin panel

Severity Rating: Medium

Vector: Denial Of Service

CVE: XXX

CWE: 400 - Uncontrolled Resource Consumption

CVSS Score: 4.9

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

Analysis

A Denial of Service (DoS) vulnerability has been identified in the application 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

Proof of Concept

1. Change the value of scheduled_at parameter to ' as shown in the following figures at the http://127.0.0.1/admin/tools endpoint, and observe the response in the second figure:

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   Figure: Http request on tool endpoint

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   Figure: Http response on tool endpoint

2. When trying to access the admin panel, the panel is broken as shown in the following figure. Additionally, the value change is reflected in the backup.yaml file, as shown in the second figure:

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   Figure: Error message view

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   Figure: Backup.yaml file

Workarounds

No workaround is currently known

Timeline

2024-07-24 Issue identified

2024-09-27 Vendor contacted

About X41 D-Sec GmbH

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Fields of expertise in the area of application security are security centered code reviews, binary reverse engineering and vulnerability discovery. Custom research and IT security consulting and support services are core competencies of X41.