The Passster WordPress plugin contains a stored XSS vulnerability due to improper neutralization of input during web page generation (CWE-79). Specifically, the content_protector shortcode does not adequately sanitize or escape user-supplied attributes, allowing authenticated contributors or higher to inject malicious scripts. These scripts execute in the context of users visiting the compromised pages, potentially leading to session hijacking or other client-side impacts. The vulnerability affects all versions up to 4.2.6.4. The CVSS 3.1 vector indicates network attack vector, low attack complexity, privileges required at low level, no user interaction, scope changed, and low impact on confidentiality and integrity, with no impact on availability.

An attacker with contributor-level or higher privileges can inject persistent malicious scripts into pages protected by the plugin. These scripts execute in the browsers of users who visit the infected pages, potentially allowing theft of session tokens, defacement, or other client-side attacks. The vulnerability does not affect availability and has low confidentiality and integrity impacts as per the CVSS score. No known active exploitation has been reported.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, restrict contributor-level access to trusted users only and consider disabling or limiting use of the content_protector shortcode. Monitor for plugin updates from wpchill and apply them promptly once available.