SPIP before 4.4.8 contains a stored cross-site scripting (XSS) vulnerability in the public area triggered in certain edge-case usage patterns. The echapper_html_suspect() function does not adequately sanitize user-controlled content, allowing authenticated users with content-editing privileges (e.g., author-level roles and above) to inject malicious scripts. The injected payload may be rendered across multiple pages within the framework and execute in the browser context of other users, including administrators. Successful exploitation can allow attackers to perform actions in the security context of the victim user, including unauthorized modification of application state. This vulnerability is not mitigated by the SPIP security screen.