CVE-2025-46491 is a Stored Cross-Site Scripting (XSS) vulnerability classified under CWE-79, affecting the Matthew Muro Multi-Column Taxonomy List plugin up to version 1.5. This vulnerability arises from improper neutralization of user-supplied input during web page generation, allowing malicious scripts to be injected and stored within the application. When a victim accesses the affected page, the malicious script executes in their browser context, potentially leading to session hijacking, credential theft, unauthorized actions on behalf of the user, or distribution of malware. Stored XSS is particularly dangerous because the payload persists on the server and can impact multiple users without requiring repeated attacker interaction. The vulnerability affects all versions of the Multi-Column Taxonomy List plugin up to 1.5, with no patch currently available. No known exploits are reported in the wild as of the publication date (April 24, 2025), but the presence of this vulnerability in a widely used WordPress plugin or similar CMS extension could facilitate targeted attacks. The lack of authentication requirements or user interaction for exploitation is typical for stored XSS, as any user visiting the compromised page may be affected. The vulnerability was identified and reserved by Patchstack and enriched by CISA, indicating recognition by authoritative cybersecurity entities.

For European organizations, this vulnerability poses a significant risk to web applications using the Matthew Muro Multi-Column Taxonomy List plugin, especially those managing content or taxonomy structures on public-facing websites. Exploitation could lead to unauthorized access to user sessions, data leakage, defacement, or the spread of malware, undermining trust and potentially violating GDPR requirements regarding data protection and breach notification. Organizations in sectors such as e-commerce, media, education, and government that rely on WordPress or similar CMS platforms with this plugin are particularly vulnerable. The persistent nature of stored XSS means multiple users can be compromised, amplifying the impact. Additionally, attackers could leverage this vulnerability as an initial foothold for more complex attacks, including privilege escalation or lateral movement within the network. The reputational damage and potential regulatory penalties for failing to secure web applications against such vulnerabilities could be substantial.

Given the absence of an official patch, European organizations should immediately audit their web environments to identify installations of the Matthew Muro Multi-Column Taxonomy List plugin, particularly versions up to 1.5. If found, organizations should consider the following specific mitigations: 1) Disable or remove the plugin until a secure version is released. 2) Implement Web Application Firewall (WAF) rules that detect and block typical XSS payload patterns targeting this plugin's endpoints or input fields. 3) Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers. 4) Conduct thorough input validation and output encoding on all user-supplied data related to taxonomy or list inputs, if custom development is possible. 5) Monitor web logs for unusual input patterns or repeated access to vulnerable pages. 6) Educate web administrators and developers about the risks of stored XSS and the importance of timely plugin updates. 7) Prepare incident response plans to quickly address any detected exploitation attempts. These measures go beyond generic advice by focusing on immediate plugin identification, removal, and compensating controls tailored to this specific vulnerability.