CVE-2025-66298 is a vulnerability categorized under CWE-1336, involving improper neutralization of special elements used in a 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, Grav's template engine fails to properly sanitize or neutralize special elements in user-supplied input submitted via POST requests to simple forms. This flaw enables an attacker to perform Server-Side Template Injection (SSTI), allowing them to execute template code that reveals the entire Grav configuration data. The configuration details include sensitive information such as plugin configurations, which may contain credentials, API keys, or other secrets. The vulnerability is remotely exploitable without authentication or user interaction, increasing its risk profile. The CVSS 4.0 base score is 7.7 (high), reflecting network attack vector, low attack complexity, no privileges or user interaction required, and high impact on confidentiality. No known exploits are currently reported in the wild, but the potential for sensitive data leakage is significant. The vulnerability was publicly disclosed on December 1, 2025, and fixed in Grav version 1.8.0-beta.27.

For European organizations, the impact of CVE-2025-66298 can be substantial. Disclosure of Grav configuration files may expose sensitive plugin settings, credentials, and other secrets, potentially leading to unauthorized access to backend systems, databases, or third-party services. This can result in data breaches, service disruptions, or lateral movement within the network. Organizations relying on Grav for public-facing websites or internal portals risk reputational damage and regulatory penalties, especially under GDPR, if personal data is exposed. The ease of exploitation without authentication increases the likelihood of automated scanning and attacks. Given Grav's popularity among small to medium enterprises and public sector entities in Europe, the threat surface is considerable. The vulnerability could also be leveraged as a foothold for more complex attacks, including ransomware or supply chain compromises.

European organizations should immediately upgrade all Grav installations to version 1.8.0-beta.27 or later to remediate this vulnerability. Until patching is possible, administrators should restrict access to forms that accept POST requests or implement web application firewall (WAF) rules to detect and block suspicious template injection payloads. Conduct thorough audits of Grav configuration files and plugin settings to identify and rotate any exposed credentials or secrets. Employ network segmentation to limit the exposure of Grav instances and monitor logs for unusual POST request patterns indicative of exploitation attempts. Additionally, implement strict input validation and output encoding in custom Grav templates or plugins to reduce the risk of SSTI. Regular vulnerability scanning and penetration testing focused on template injection vectors are recommended to proactively detect similar issues.