CVE-2025-66298 is a vulnerability classified 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 popular for its simplicity and flexibility. 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 allows an attacker to perform Server-Side Template Injection (SSTI), enabling them to execute template code that reveals the entire Grav configuration, including sensitive plugin configuration details. The configuration data may contain credentials, API keys, or other sensitive information that could be leveraged for further compromise. The vulnerability is remotely exploitable without authentication or user interaction, increasing its risk profile. The CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), and high impact on confidentiality (VC:H) but no impact on integrity or availability. Although no exploits have been reported in the wild, the vulnerability's nature and ease of exploitation make it a significant threat to affected systems. The issue was addressed in Grav version 1.8.0-beta.27 by properly neutralizing special template elements in user inputs, preventing unauthorized disclosure of configuration data.

For European organizations, this vulnerability poses a substantial risk of sensitive information leakage from Grav-based web platforms. Disclosure of configuration and plugin details can lead to credential exposure, unauthorized access, and further exploitation such as privilege escalation or lateral movement within networks. Organizations relying on Grav for public-facing websites or internal portals may face data breaches, reputational damage, and compliance violations under GDPR due to unauthorized data exposure. The lack of authentication requirement and ease of exploitation increase the likelihood of automated scanning and attacks. Critical sectors such as government, finance, healthcare, and e-commerce in Europe that use Grav could experience service disruptions or data compromise. Additionally, attackers could leverage disclosed configuration details to deploy malware or ransomware, amplifying the operational impact. The vulnerability's exploitation could also undermine trust in digital services and necessitate costly incident response and remediation efforts.

European organizations should immediately upgrade all Grav installations to version 1.8.0-beta.27 or later to remediate this vulnerability. Until patching is complete, restrict access to web forms that accept POST requests by implementing IP whitelisting or web application firewall (WAF) rules to detect and block suspicious template injection payloads. Conduct thorough audits of Grav configurations and plugin settings to identify and remove any exposed sensitive data. Enable detailed logging and monitoring of HTTP POST requests to detect anomalous activity indicative of exploitation attempts. Employ network segmentation to isolate Grav servers from critical internal systems, limiting potential lateral movement. Educate web administrators on secure template handling and the risks of SSTI vulnerabilities. Regularly review and update incident response plans to include scenarios involving template injection attacks. Finally, consider deploying runtime application self-protection (RASP) tools that can detect and block SSTI attempts in real time.