CVE-2025-11803 is a stored cross-site scripting (XSS) vulnerability identified in the WPSite Shortcode plugin for WordPress, specifically affecting all versions up to and including 1.2. The vulnerability arises from improper neutralization of input during web page generation, classified under CWE-79. It involves insufficient sanitization and output escaping of user-supplied data in the 'format' attribute of the wpsite_y shortcode and the 'before' attribute of the wpsite_postauthor shortcode. Authenticated attackers with contributor-level privileges or higher can exploit this flaw by injecting arbitrary JavaScript code into these shortcode attributes. Because the malicious script is stored, it executes in the context of any user who visits the infected page, potentially compromising user sessions, stealing cookies, or performing unauthorized actions on behalf of users. The vulnerability has a CVSS 3.1 base score of 6.4, reflecting medium severity, with an attack vector of network, low attack complexity, privileges required at the level of a contributor, no user interaction needed, and a scope change indicating impact beyond the vulnerable component. No public exploits have been reported yet, but the risk remains significant due to the widespread use of WordPress and the plugin. The vulnerability affects all versions of the plugin up to 1.2, and no official patches or updates are currently linked, emphasizing the need for immediate mitigation efforts by administrators.

For European organizations, this vulnerability poses a risk primarily to websites using the WPSite Shortcode plugin on WordPress platforms. Exploitation could lead to session hijacking, unauthorized actions performed under the guise of legitimate users, defacement, or distribution of malware through compromised web pages. Given the stored nature of the XSS, any visitor to the infected page is at risk, potentially including customers, partners, or employees accessing the site. This can damage organizational reputation, lead to data breaches involving user credentials or personal data, and result in regulatory non-compliance under GDPR if personal data is exposed or mishandled. The medium severity score reflects a moderate but tangible threat, especially since exploitation requires authenticated access, limiting the attacker pool but not eliminating risk in environments with multiple contributors or editors. The lack of known exploits in the wild reduces immediate urgency but does not diminish the importance of remediation, as attackers could develop exploits rapidly once the vulnerability is public.

European organizations should immediately audit their WordPress installations to identify the presence of the WPSite Shortcode plugin and verify the version in use. Since no official patches are currently linked, administrators should consider the following specific mitigations: 1) Restrict contributor-level access strictly to trusted users to reduce the risk of malicious input injection. 2) Implement web application firewall (WAF) rules to detect and block suspicious shortcode attribute inputs containing script tags or JavaScript event handlers. 3) Employ Content Security Policy (CSP) headers to limit the execution of inline scripts and reduce the impact of any injected scripts. 4) Sanitize and validate all shortcode inputs at the application level if custom modifications are possible. 5) Monitor logs for unusual shortcode usage or error messages indicating attempted exploitation. 6) Prepare to update or replace the plugin once a vendor patch is released. 7) Educate content contributors about the risks of injecting untrusted content into shortcodes. These targeted actions go beyond generic advice and address the specific vectors and conditions of this vulnerability.