CVE-2025-50286 is a high-severity Remote Code Execution (RCE) vulnerability affecting Grav CMS version 1.7.48. Grav CMS is a flat-file content management system widely used for building websites without a traditional database backend. This vulnerability arises from the /admin/tools/direct-install interface, which allows authenticated administrators to upload plugins. Due to insufficient validation or sanitization of uploaded plugin packages, an attacker with admin credentials can upload a malicious plugin archive. Upon upload, the system automatically extracts and loads the plugin, enabling the execution of arbitrary PHP code within the context of the web server. This can lead to a full reverse shell, granting the attacker remote control over the affected server. The vulnerability is categorized under CWE-434 (Unrestricted Upload of File with Dangerous Type), indicating that the system does not properly restrict or validate the types of files being uploaded. The CVSS v3.1 base score is 8.1, reflecting a high severity with network attack vector, high attack complexity, no privileges required, no user interaction, and high impact on confidentiality, integrity, and availability. Although exploitation requires an authenticated admin user, the impact of successful exploitation is severe, potentially allowing complete system compromise. No public exploits are currently known in the wild, and no patches or fixes have been linked yet. This vulnerability highlights the risk of insufficient input validation in administrative upload interfaces and the critical need to secure plugin installation mechanisms in CMS platforms.

For European organizations using Grav CMS, this vulnerability poses a significant risk. Organizations relying on Grav CMS for public-facing websites or internal portals could face full system compromise if an attacker gains admin access. The ability to execute arbitrary PHP code and establish reverse shells can lead to data breaches, defacement, lateral movement within internal networks, and disruption of services. Confidential information stored or processed by the CMS could be exfiltrated, and attackers could use compromised servers as pivot points for further attacks. Given the high impact on confidentiality, integrity, and availability, organizations could suffer reputational damage, regulatory penalties under GDPR for data breaches, and operational downtime. The requirement for admin authentication somewhat limits the attack surface; however, credential theft, phishing, or insider threats could facilitate exploitation. European entities with less mature access controls or weak admin credential management are particularly vulnerable. Additionally, organizations that do not regularly update or audit their CMS installations may remain exposed for extended periods.

To mitigate this vulnerability effectively, European organizations should: 1) Immediately restrict access to the Grav CMS admin interface using network-level controls such as VPNs, IP whitelisting, or multi-factor authentication (MFA) to reduce the risk of unauthorized admin access. 2) Enforce strong password policies and implement MFA for all admin accounts to prevent credential compromise. 3) Monitor and audit admin activities and plugin uploads for suspicious behavior or unauthorized changes. 4) Disable or restrict the /admin/tools/direct-install interface if plugin installation is not frequently required, or replace it with a manual plugin installation process that includes integrity verification. 5) Apply any available patches or updates from Grav CMS as soon as they are released. 6) Conduct regular security assessments and penetration testing focused on CMS components. 7) Implement web application firewalls (WAFs) with rules to detect and block malicious payloads or unusual plugin upload patterns. 8) Educate administrators on phishing and social engineering risks to protect admin credentials. These measures go beyond generic advice by focusing on reducing the likelihood of admin credential compromise and limiting the attack surface of the vulnerable interface.