CVE-2025-66844 is a critical SSRF vulnerability identified in Grav CMS versions earlier than 1.7.49.5. Grav is a flat-file content management system that uses Twig as its templating engine. The vulnerability occurs when page content is processed by Twig templates and the system configuration allows undefined PHP functions to be registered. This misconfiguration enables an attacker to craft malicious requests that cause the server to perform unauthorized HTTP requests to internal or external resources. SSRF vulnerabilities like this can be leveraged to bypass network access controls, scan internal networks, access sensitive metadata services, or interact with backend systems that are otherwise inaccessible externally. The vulnerability has a CVSS v3.1 base score of 9.1, reflecting its network attack vector, low attack complexity, no privileges or user interaction required, and high impact on confidentiality and integrity. Although no public exploits have been reported yet, the critical nature of the flaw and the widespread use of Grav CMS in web hosting environments make it a significant threat. The vulnerability is tracked under CWE-918 (Server-Side Request Forgery). No official patches or updates are linked in the provided data, but the fixed version is 1.7.49.5 or later, indicating that upgrading is the primary remediation. Organizations using Grav CMS should audit their Twig template configurations to ensure undefined PHP functions cannot be registered, reducing the attack surface. This vulnerability highlights the risks of insecure template processing and improper configuration management in web applications.

For European organizations, the impact of CVE-2025-66844 can be severe. Exploitation can lead to unauthorized internal network access, data exfiltration, and potential lateral movement within corporate networks. Confidentiality is highly impacted as attackers may access sensitive internal services or data repositories. Integrity is also at risk if attackers manipulate server-side requests to alter data or configurations indirectly. Availability impact is low, but the breach of confidentiality and integrity can cause significant operational and reputational damage. Organizations relying on Grav CMS for public websites, intranet portals, or customer-facing applications are particularly vulnerable. Given the critical CVSS score and the lack of required authentication, attackers can exploit this vulnerability remotely and without user interaction, increasing the risk of automated mass scanning and exploitation attempts. European sectors such as finance, healthcare, government, and critical infrastructure that use Grav CMS or similar templating configurations face heightened risk. The vulnerability could also be leveraged in multi-stage attacks targeting internal network resources behind firewalls, which are otherwise protected from direct external access.

1. Immediately upgrade Grav CMS installations to version 1.7.49.5 or later where the vulnerability is patched. 2. Audit and harden Twig template configurations to disallow registration or invocation of undefined PHP functions, preventing SSRF vectors. 3. Implement strict input validation and sanitization on any user-controllable content processed by Twig templates. 4. Employ network segmentation and firewall rules to restrict outbound HTTP requests from web servers to only necessary destinations, limiting SSRF impact. 5. Monitor web server logs and network traffic for unusual outbound requests indicative of SSRF exploitation attempts. 6. Use Web Application Firewalls (WAFs) with rules designed to detect and block SSRF attack patterns targeting Grav CMS. 7. Conduct regular security assessments and code reviews focusing on template processing and server-side request handling. 8. Educate development and operations teams about secure template usage and configuration best practices to prevent similar vulnerabilities.