CVE-2025-11241 is a stored Cross-Site Scripting (XSS) vulnerability affecting the Yoast SEO Premium WordPress plugin, specifically versions 25.7 to 25.9. The vulnerability arises from a flawed regular expression used by the plugin to sanitize post content by removing certain attributes. This regex fails to properly neutralize script-related HTML tags and attributes, allowing an attacker with Contributor-level access or higher to inject arbitrary HTML attributes, including JavaScript event handlers, into posts. Because the malicious payload is stored in the post content, it will be served to any user viewing the post, potentially executing the injected JavaScript in their browser context. The vulnerability has a CVSS 3.1 base score of 6.4, indicating a medium severity level. The attack vector is network-based, requires low attack complexity, and privileges of a user with Contributor role or higher, but does not require user interaction for exploitation. The scope is changed, meaning the vulnerability can affect components beyond the initially vulnerable plugin, such as other parts of the WordPress site or user sessions. The impact affects confidentiality and integrity, allowing attackers to potentially steal session cookies, perform actions on behalf of other users, or manipulate site content. No known exploits have been reported in the wild as of the publication date. The vulnerability is classified under CWE-80, which corresponds to improper neutralization of script-related HTML tags in web pages, a common cause of XSS issues. The flaw is specifically due to insufficient sanitization in the regex pattern used to remove attributes, which can be bypassed to inject malicious JavaScript event handlers.

For European organizations using WordPress sites with the Yoast SEO Premium plugin versions 25.7 to 25.9, this vulnerability poses a significant risk. Since Contributor-level users can exploit this flaw, insider threats or compromised contributor accounts can lead to persistent XSS attacks. The injected scripts can steal sensitive information such as authentication cookies, enabling session hijacking, or perform unauthorized actions on behalf of other users, including administrators. This can lead to data breaches, defacement, or further compromise of the web infrastructure. The impact is particularly critical for organizations handling personal data under GDPR, as exploitation could lead to unauthorized data access or modification, resulting in regulatory penalties and reputational damage. Additionally, the vulnerability could be leveraged to distribute malware or phishing content to site visitors, affecting customer trust and business continuity. The medium CVSS score reflects the need for timely remediation, especially in environments with multiple contributors or public-facing content. The lack of known exploits in the wild suggests an opportunity for proactive mitigation before widespread abuse occurs.

European organizations should immediately identify WordPress installations running Yoast SEO Premium versions 25.7 to 25.9. Since no official patch links are provided, organizations should monitor Yoast's official channels for updates or patches addressing CVE-2025-11241. In the interim, restrict Contributor-level user permissions to trusted personnel only and audit existing posts created by contributors for suspicious content or injected scripts. Implement Web Application Firewall (WAF) rules to detect and block common XSS payload patterns targeting the affected plugin. Employ Content Security Policy (CSP) headers to limit the execution of inline scripts and reduce the impact of potential XSS payloads. Regularly scan the website with specialized tools capable of detecting stored XSS vulnerabilities. Additionally, consider disabling or downgrading the plugin to a non-vulnerable version if feasible until a patch is available. Educate content contributors about safe content practices and the risks of injecting untrusted code. Finally, ensure that all WordPress core and plugins are kept up to date to minimize exposure to similar vulnerabilities.