Overview
CVE-2025-66301 identifies a critical vulnerability in Grav, a file-based web platform. This flaw, present in versions prior to 1.8.0-beta.27, allows users with limited editing permissions to manipulate the YAML frontmatter, potentially leading to severe security consequences. Specifically, an editor who only has rights to edit basic content can modify the data[_json][header][form] section which dictates the form process after a user submits it. This can lead to further exploitation.
Technical Details
The vulnerability stems from insufficient authorization checks when handling POST requests to /admin/pages/{page_name}. An editor with permissions to modify basic content can alter critical fields within the data[_json][header][form] section of the YAML frontmatter. This section controls the form processing logic after submission. The ability to manipulate the process section allows an attacker to potentially execute arbitrary code, inject malicious content, or redirect users to phishing sites. The core problem is that the frontmatter dictates what happens after a user submits a form including important actions, and this section was modifiable by users who should not have been able to change it.
CVSS Analysis
Currently, a CVSS score has not been assigned to CVE-2025-66301 (N/A). However, given the potential for arbitrary code execution and other serious impacts, this vulnerability should be considered high severity. A full CVSS analysis will be conducted as more information becomes available.
Possible Impact
The exploitation of CVE-2025-66301 can have several significant consequences:
- Arbitrary Code Execution: An attacker could modify the form processing logic to execute arbitrary code on the server.
- Cross-Site Scripting (XSS): Malicious JavaScript could be injected into the frontmatter, allowing for XSS attacks.
- Phishing: Users could be redirected to fraudulent websites designed to steal credentials.
- Data Manipulation: Sensitive data could be altered or stolen.
- Denial of Service (DoS): The server could be rendered unavailable due to malicious code execution.
Mitigation and Patch Steps
The vulnerability is fixed in Grav version 1.8.0-beta.27. It is strongly recommended that all Grav users upgrade to this version or a later version immediately. If upgrading is not immediately possible, consider implementing temporary workarounds, such as restricting access to the admin panel based on IP address or using a Web Application Firewall (WAF) to filter malicious requests.
To upgrade Grav:
- Log into the Grav Admin Panel.
- Navigate to the “Plugins” or “Themes” section.
- Click the “Upgrades” button to update to the latest version.
