CVE-2025-39509 describes a stored cross-site scripting vulnerability in the ThemeNcode TNC FlipBook WordPress plugin (versions <= 12.1.0). The issue is caused by improper neutralization of input during web page generation, which allows attackers to inject malicious scripts that persist and execute in the context of other users viewing the affected content. The vulnerability has a CVSS 3.1 score of 6.5, reflecting medium severity with network attack vector, low attack complexity, low privileges required, and user interaction necessary. The vulnerability impacts confidentiality, integrity, and availability of affected systems. No patch or vendor advisory is currently available, and no known active exploitation has been reported.

Successful exploitation of this vulnerability could allow an attacker to execute arbitrary scripts in the context of users viewing the affected FlipBook content. This can lead to partial compromise of confidentiality, integrity, and availability of user data or sessions. The medium CVSS score reflects that the attack requires user interaction and low privileges but can have a significant impact if exploited.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, users should consider disabling or limiting use of the affected TNC FlipBook plugin versions. Monitor for updates from ThemeNcode and apply patches promptly once available. No vendor advisory or official fix information is currently provided.