The WP SPID Italia plugin for WordPress, used to integrate Italy's SPID digital identity system, contains a stored Cross-Site Scripting (XSS) vulnerability identified as CVE-2024-11758. This vulnerability arises from improper neutralization of user-supplied input in shortcode attributes, where the plugin fails to adequately sanitize and escape input before rendering it on web pages. Authenticated attackers with contributor-level permissions or higher can exploit this flaw by injecting arbitrary JavaScript code into pages via the plugin's shortcode functionality. Because the malicious script is stored persistently, it executes every time a user accesses the infected page, potentially compromising user sessions, stealing cookies, or performing unauthorized actions on behalf of users. The vulnerability affects all versions up to and including 2.9 of the plugin. The CVSS 3.1 base score is 6.4, reflecting network attack vector, low attack complexity, privileges required, no user interaction, and a scope change with limited confidentiality and integrity impact but no availability impact. No public exploit code or active exploitation has been reported yet. The vulnerability is classified under CWE-79, highlighting improper input validation and output encoding as the root cause. Given the plugin's role in handling identity-related functionality, exploitation could have serious consequences if leveraged in targeted attacks.

This vulnerability poses a moderate risk to organizations using the WP SPID Italia plugin, particularly those relying on WordPress sites for identity verification or public services in Italy. Exploitation could lead to session hijacking, unauthorized actions performed with victim user privileges, defacement, or redirection to malicious sites. Since contributor-level access is required, attackers must first compromise or have legitimate access to user accounts with these permissions, which limits the attack surface but does not eliminate risk. The persistent nature of stored XSS means multiple users can be affected once the malicious payload is injected. Confidentiality and integrity of user data and sessions are at risk, potentially undermining trust in affected websites. Organizations could face reputational damage, regulatory scrutiny, and user impact if exploited. The lack of known exploits in the wild suggests the threat is currently low but could increase if exploit code is developed and shared.

Organizations should immediately update the WP SPID Italia plugin to a patched version once available, or apply vendor-recommended fixes. In the absence of a patch, administrators should restrict contributor-level access to trusted users only and audit existing content for injected scripts. Implementing a Web Application Firewall (WAF) with rules to detect and block malicious script payloads in shortcode attributes can provide temporary protection. Additionally, site owners should enable Content Security Policy (CSP) headers to restrict script execution sources and reduce XSS impact. Regularly scanning WordPress sites with security plugins that detect XSS and other injection flaws is recommended. Developers maintaining the plugin should adopt secure coding practices including rigorous input validation, output encoding, and use of WordPress security APIs for shortcode handling. Monitoring logs for suspicious activity related to shortcode usage can help detect exploitation attempts early.