CVE-2025-29011 is a Stored Cross-Site Scripting (XSS) vulnerability classified under CWE-79, affecting the CHR Designer YouTube Simple Gallery plugin up to version 2.2.0. The vulnerability arises due to improper neutralization of input during web page generation, allowing malicious scripts to be injected and stored within the application. When a victim accesses the affected page, the malicious script executes in their browser context. This can lead to unauthorized actions such as session hijacking, defacement, or redirection to malicious sites. The vulnerability requires low attack complexity (AC:L), network attack vector (AV:N), and privileges (PR:L) with user interaction (UI:R) needed to trigger the exploit. The scope is changed (S:C), meaning the vulnerability affects resources beyond the vulnerable component. The CVSS v3.1 base score is 6.5, indicating a medium severity level. Although no known exploits are currently in the wild, the vulnerability poses a tangible risk due to the common use of web galleries and the potential for stored XSS to facilitate persistent attacks. The lack of available patches at the time of publication increases exposure risk for users of affected versions. The vulnerability impacts confidentiality, integrity, and availability to a limited extent but can be leveraged as a foothold for further attacks.

For European organizations, this vulnerability can compromise web applications that utilize the CHR Designer YouTube Simple Gallery plugin, potentially exposing users to session hijacking, credential theft, or unauthorized actions performed on behalf of users. This is particularly concerning for organizations relying on this plugin for public-facing websites or intranet portals, as attackers could inject malicious payloads that affect a broad user base. The stored nature of the XSS means that once injected, the malicious script persists, increasing the risk of widespread exploitation. Organizations in sectors such as media, education, and e-commerce that embed video galleries are at higher risk. Additionally, the vulnerability could be exploited to bypass security controls or deliver secondary payloads, impacting compliance with GDPR and other data protection regulations due to potential data leakage or unauthorized access.

1. Immediate review and sanitization of all user inputs that interact with the YouTube Simple Gallery plugin to ensure proper encoding and neutralization of HTML and script content. 2. Implement Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts and reduce the impact of XSS attacks. 3. Restrict privileges required to manage or upload content in the gallery plugin to trusted users only, minimizing the risk of malicious input injection. 4. Monitor web application logs for unusual input patterns or script injection attempts related to the gallery plugin. 5. Until an official patch is released, consider disabling or removing the YouTube Simple Gallery plugin if it is not essential. 6. Educate users and administrators about the risks of stored XSS and encourage prompt reporting of suspicious website behavior. 7. Employ web application firewalls (WAF) with rules tailored to detect and block XSS payloads targeting this plugin. 8. Regularly update and audit all third-party plugins and dependencies to ensure timely application of security patches.