CVE-2025-47621 is a security vulnerability classified as CWE-79, which refers to Improper Neutralization of Input During Web Page Generation, commonly known as Cross-site Scripting (XSS). This vulnerability affects the Meks Flexible Shortcodes plugin, versions up to and including 1.3.6. The issue allows an attacker to inject malicious scripts that are stored and later executed in the context of the victim's browser when they visit a page containing the vulnerable shortcode. This stored XSS can lead to unauthorized actions such as session hijacking, defacement, or redirection to malicious sites. The vulnerability arises because the plugin does not properly sanitize or neutralize user input before rendering it on web pages, allowing malicious payloads to be embedded and persistently stored. The CVSS v3.1 base score is 6.5, indicating a medium severity level. The vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L) shows that the attack can be performed remotely over the network with low attack complexity, requires low privileges, and user interaction is needed. The scope is changed, meaning the vulnerability affects components beyond the initially vulnerable component. The impact includes low confidentiality, integrity, and availability impacts, but the stored nature of the XSS increases its risk profile. No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability was published on May 7, 2025, and has been enriched by CISA, indicating recognition by US cybersecurity authorities.

For European organizations, the impact of this stored XSS vulnerability can be significant, especially for those using the Meks Flexible Shortcodes plugin on their websites or web applications. Exploitation could lead to theft of user credentials, session tokens, or other sensitive information, potentially resulting in unauthorized access to user accounts or administrative functions. This can damage the organization's reputation, lead to data breaches, and cause regulatory compliance issues under GDPR due to exposure of personal data. Additionally, attackers could use the vulnerability to deliver malware or conduct phishing attacks by modifying website content. The medium severity score reflects that while the vulnerability requires some user interaction and low privileges, the potential for persistent exploitation and scope change elevates the risk. Organizations with customer-facing websites or portals using this plugin are particularly at risk, as attackers can target end-users directly. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate it, as attackers may develop exploits once the vulnerability becomes widely known.

European organizations should take the following specific actions to mitigate this vulnerability: 1) Immediately identify all instances of the Meks Flexible Shortcodes plugin in use across their web properties and inventory the versions deployed. 2) Monitor the vendor's official channels and security advisories for the release of patches or updates addressing CVE-2025-47621 and apply them promptly once available. 3) Implement Web Application Firewall (WAF) rules that can detect and block typical XSS payloads targeting the affected shortcode parameters, providing a temporary protective layer. 4) Conduct thorough input validation and output encoding on all user-supplied data related to shortcode inputs, even if the plugin is updated, to reduce risk from other potential injection points. 5) Educate web administrators and developers about the risks of stored XSS and the importance of sanitizing inputs in custom shortcode implementations. 6) Review and enhance Content Security Policy (CSP) headers to restrict script execution sources, limiting the impact of any injected scripts. 7) Perform regular security testing, including automated scans and manual penetration testing focused on XSS vulnerabilities, to detect any residual or new issues. These measures go beyond generic advice by focusing on immediate detection, temporary protection, and long-term secure coding practices tailored to the specific plugin and vulnerability.