CVE-2025-4169 is a medium-severity vulnerability classified as CWE-79 (Improper Neutralization of Input During Web Page Generation, commonly known as Cross-site Scripting or XSS) affecting the 'Posts per Cat' WordPress plugin developed by urkekg. This plugin, which is currently unmaintained, suffers from a Stored Cross-Site Scripting vulnerability in all versions up to and including 1.4.2. The vulnerability arises due to insufficient sanitization and escaping of user-supplied attributes within the plugin's 'ppc' shortcode. Authenticated users with contributor-level privileges or higher can exploit this flaw by injecting arbitrary malicious scripts into pages generated by the plugin. These scripts are persistently stored and executed whenever any user accesses the compromised page, potentially leading to session hijacking, privilege escalation, or redirection to malicious sites. The CVSS v3.1 base score is 6.4, indicating a medium severity level, with the attack vector being network-based, low attack complexity, requiring privileges (PR:L) but no user interaction (UI:N), and impacting confidentiality and integrity with a scope change (S:C). No patches or fixes have been published yet, and there are no known exploits in the wild at this time. The vulnerability was published on May 16, 2025, with enrichment from CISA and assignment by Wordfence. Since the plugin is unmaintained, the risk of exploitation may increase over time as no official remediation is forthcoming.

For European organizations using WordPress websites with the 'Posts per Cat' plugin installed, this vulnerability presents a significant risk. Attackers with contributor-level access can inject malicious scripts that execute in the context of site visitors or administrators, potentially leading to theft of authentication tokens, unauthorized actions, defacement, or distribution of malware. This can damage organizational reputation, lead to data breaches involving personal data protected under GDPR, and cause operational disruptions. Since the vulnerability allows scope change, an attacker could leverage this to escalate privileges or move laterally within the web application environment. The impact is particularly critical for organizations relying on WordPress for public-facing content, e-commerce, or internal portals where contributor roles are assigned. The lack of patch availability and the plugin's unmaintained status increase the risk exposure, especially for organizations with limited monitoring or security controls on their CMS environments.

Given the absence of official patches, European organizations should take immediate practical steps to mitigate this vulnerability. First, audit all WordPress installations to identify the presence of the 'Posts per Cat' plugin and its version. If found, disable or uninstall the plugin to eliminate the attack surface. If the plugin functionality is essential, consider replacing it with a maintained alternative that provides similar features with secure coding practices. Restrict contributor-level access strictly to trusted users and review user roles to minimize the number of accounts with such privileges. Implement Web Application Firewall (WAF) rules to detect and block suspicious shortcode attribute inputs that may contain script tags or malicious payloads. Enable Content Security Policy (CSP) headers to reduce the impact of any injected scripts by restricting script execution sources. Regularly monitor logs for unusual activity related to shortcode usage or page modifications. Finally, educate site administrators and contributors about the risks of injecting untrusted content and encourage prompt reporting of suspicious behavior.