CVE-2025-55422 is a high-severity reflected Cross Site Scripting (XSS) vulnerability identified in FoxCMS version 1.2.6, specifically within the /index.php/plus endpoint. Reflected XSS vulnerabilities occur when untrusted user input is immediately returned by a web application without proper sanitization or encoding, allowing attackers to inject malicious scripts into the victim's browser. In this case, the vulnerability enables an attacker to craft a specially crafted URL or request that, when visited by a user, executes arbitrary JavaScript code in the context of the vulnerable FoxCMS site. The CVSS score of 8.8 (High) reflects the potential for significant impact, including full compromise of user session confidentiality, integrity, and availability. The CVSS vector indicates that the attack can be performed remotely over the network without any privileges or authentication (AV:N/AC:L/PR:N), but requires user interaction (UI:R) such as clicking a malicious link. The scope is unchanged (S:U), meaning the vulnerability affects only the vulnerable component. The impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H), meaning an attacker can steal sensitive data, manipulate content, or disrupt service. No known exploits are currently reported in the wild, and no patches or fixes have been linked yet. The vulnerability is classified under CWE-79, which is the standard identifier for Cross Site Scripting issues. Given the nature of FoxCMS as a content management system, this vulnerability could be leveraged to perform phishing attacks, session hijacking, defacement, or distribution of malware to site visitors.

For European organizations using FoxCMS 1.2.6, this vulnerability poses a significant risk. Attackers exploiting this XSS flaw can hijack user sessions, steal credentials, or perform actions on behalf of legitimate users, potentially leading to data breaches or unauthorized access to sensitive information. This is particularly critical for organizations handling personal data under GDPR, as exploitation could result in regulatory penalties and reputational damage. Additionally, the ability to inject malicious scripts can facilitate the spread of malware or ransomware, disrupt business operations, and erode customer trust. Since FoxCMS is a web-facing platform, the attack surface is broad, and any public-facing FoxCMS deployment in Europe is at risk. The requirement for user interaction means social engineering or phishing campaigns could be used to lure victims to malicious URLs. The lack of an available patch increases the urgency for organizations to implement interim mitigations. Overall, the vulnerability threatens confidentiality, integrity, and availability of affected systems and data, with potential cascading effects on business continuity and compliance obligations.

Given the absence of an official patch, European organizations should implement several targeted mitigations: 1) Employ Web Application Firewalls (WAFs) with custom rules to detect and block malicious payloads targeting the /index.php/plus endpoint, focusing on typical XSS attack patterns. 2) Implement strict Content Security Policy (CSP) headers to restrict execution of unauthorized scripts and reduce the impact of injected code. 3) Conduct thorough input validation and output encoding on all user-supplied data within FoxCMS, especially in the vulnerable endpoint, to neutralize malicious scripts. 4) Educate users and administrators about phishing risks and encourage cautious behavior when clicking on links, particularly those received via email or untrusted sources. 5) Monitor web server logs and application behavior for unusual requests or error patterns indicative of exploitation attempts. 6) Plan and prioritize upgrading or patching FoxCMS as soon as a fix becomes available, and consider temporary isolation or limited exposure of vulnerable instances. 7) Use security scanners to identify vulnerable FoxCMS installations within the organization’s environment to ensure comprehensive coverage.