CVE-2025-66297 is a vulnerability classified under CWE-1336, involving improper neutralization of special elements used in the Twig template engine within the Grav CMS platform. Grav is a file-based web platform widely used for content management. Prior to version 1.8.0-beta.27, users with admin panel access and permissions to create or edit pages can enable Twig processing in the page frontmatter. This feature allows the execution of Twig expressions embedded in page metadata. Due to insufficient sanitization of these expressions, an attacker with these privileges can inject malicious Twig code that the system executes. This injection enables escalation of privileges to full administrator rights and allows arbitrary system command execution through the scheduler API. The vulnerability does not require additional authentication or user interaction beyond the initial admin-level access, making it highly dangerous if admin credentials are compromised or misused. The CVSS 4.0 base score is 7.4 (high severity), reflecting network attack vector, low attack complexity, no privileges required beyond limited admin access, and high impact on confidentiality, integrity, and availability. The flaw is fixed in Grav version 1.8.0-beta.27. No public exploits have been reported yet, but the potential for exploitation is significant given the nature of the vulnerability.

For European organizations using Grav CMS versions prior to 1.8.0-beta.27, this vulnerability poses a serious risk. An attacker with limited admin panel access can escalate privileges to full admin and execute arbitrary system commands, potentially leading to complete system compromise. This can result in data breaches, defacement, service disruption, or use of the compromised system as a pivot point for further attacks within the network. The impact on confidentiality, integrity, and availability is high. Organizations in sectors with sensitive data or critical services, such as government, finance, healthcare, and media, are particularly at risk. The file-based nature of Grav CMS means that compromised systems could also affect website content integrity and availability, damaging reputation and trust. Since the vulnerability requires admin panel access, the risk is amplified in environments with weak access controls or where admin credentials are shared or poorly managed.

European organizations should immediately upgrade Grav CMS installations to version 1.8.0-beta.27 or later to remediate this vulnerability. Until patching is possible, restrict admin panel access strictly to trusted personnel and enforce strong authentication mechanisms, such as multi-factor authentication (MFA). Review and limit permissions so that only necessary users can create or edit pages with Twig processing enabled. Disable Twig processing in page frontmatter if not required. Monitor scheduler API usage and logs for suspicious activity indicative of command execution attempts. Implement network segmentation to isolate CMS servers and reduce lateral movement risk. Conduct regular audits of admin accounts and credentials to detect unauthorized access. Employ web application firewalls (WAFs) with custom rules to detect and block malicious Twig expressions if feasible. Finally, maintain an incident response plan tailored to CMS compromises to enable rapid containment and recovery.