Overview
CVE-2025-66294 describes a Server-Side Template Injection (SSTI) vulnerability found in Grav, a file-based web platform. This vulnerability affects Grav versions prior to 1.8.0-beta.27. Exploitation of this flaw allows authenticated attackers with editor permissions to execute arbitrary commands on the server. Under certain conditions, unauthenticated attackers might also be able to exploit this vulnerability.
Technical Details
The root cause of this vulnerability lies in the weak regex validation within the cleanDangerousTwig method of Grav. This method, intended to sanitize user input to prevent malicious Twig code injection, fails to adequately filter out potentially harmful constructs. Attackers can leverage this weakness to inject arbitrary Twig code, ultimately leading to command execution on the server.
CVSS Analysis
While the NVD and other sources may not have assigned a specific CVSS score yet, the nature of this vulnerability points to a high severity. The ability to execute arbitrary commands on a server through SSTI poses a significant risk. A CVSS score will likely be assigned soon, which would categorize it as Critical.
Possible Impact
The exploitation of CVE-2025-66294 can have severe consequences:
- Remote Code Execution (RCE): Attackers can execute arbitrary commands on the server, potentially leading to a complete system compromise.
- Data Breach: Attackers can access sensitive data stored on the server, including configuration files, database credentials, and user data.
- Website Defacement: Attackers can modify the website’s content, deface the site, or inject malicious code.
- Denial of Service (DoS): Attackers can disrupt the website’s availability by crashing the server or overloading it with requests.
Mitigation and Patch Steps
The recommended mitigation is to upgrade your Grav installation to version 1.8.0-beta.27 or later. This version contains a fix for the weak regex validation in the cleanDangerousTwig method, effectively preventing the SSTI vulnerability. If you cannot upgrade immediately, consider implementing temporary workarounds, such as restricting access to editor permissions to only trusted users and carefully sanitizing user input.
