CVE-2025-13705 is a stored Cross-Site Scripting (XSS) vulnerability identified in the Custom Frames plugin for WordPress, developed by blakelong. The vulnerability exists due to improper neutralization of input during web page generation, specifically in the handling of the 'class' parameter within the 'customframe' shortcode. All versions up to and including 1.0.1 are affected. An attacker with authenticated access at the Contributor level or higher can inject arbitrary JavaScript code into pages by manipulating this parameter. Because the injected scripts are stored and rendered whenever the page is accessed, this can lead to persistent XSS attacks impacting any user who views the compromised content. The vulnerability is classified under CWE-79, indicating improper input sanitization and output escaping. The CVSS v3.1 base score is 6.4, reflecting a medium severity with network attack vector, low attack complexity, requiring privileges but no user interaction, and a scope change affecting confidentiality and integrity but not availability. Although no known exploits are reported in the wild, the vulnerability poses a significant risk to WordPress sites using this plugin, especially those that allow multiple contributors to publish content. The exploitation can lead to session hijacking, unauthorized actions on behalf of users, or distribution of malware. The lack of a patch at the time of reporting necessitates immediate attention to mitigate risk.

For European organizations, this vulnerability presents a moderate risk primarily to websites and web applications running WordPress with the Custom Frames plugin installed. The ability for authenticated contributors to inject persistent malicious scripts can compromise the confidentiality and integrity of user sessions and data. This can lead to unauthorized access, data theft, defacement, or distribution of malware to site visitors. Organizations relying on WordPress for content management, especially those with multiple contributors or editors, are at higher risk. The impact is heightened for sectors with strict data protection regulations such as GDPR, where data breaches could result in regulatory penalties and reputational damage. Additionally, compromised websites can be leveraged as attack vectors against customers or partners, amplifying the threat. The medium severity score reflects the need for timely remediation but indicates that exploitation requires some level of privilege, limiting immediate widespread impact. However, given WordPress's popularity across Europe, the potential attack surface is significant.

1. Monitor the vendor’s official channels for a security patch and apply updates immediately once available. 2. Until a patch is released, restrict Contributor-level access or higher to trusted users only, minimizing the risk of malicious script injection. 3. Implement Web Application Firewall (WAF) rules to detect and block suspicious input patterns targeting the 'class' parameter in the 'customframe' shortcode. 4. Employ additional input validation and output encoding on the server side to sanitize the 'class' parameter, ensuring no executable scripts can be injected. 5. Conduct regular security audits and code reviews of custom plugins and shortcodes to identify similar vulnerabilities. 6. Educate content contributors about safe content publishing practices and the risks of injecting untrusted code. 7. Use Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts on affected websites. 8. Monitor website logs and user activity for signs of exploitation or unusual behavior related to content editing and page rendering.