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. The root cause is insufficient input sanitization and output escaping, which allows an authenticated attacker with Contributor-level access or higher to inject arbitrary JavaScript code into pages. This malicious code is stored persistently and executes whenever any user accesses the infected page, potentially compromising user sessions, stealing cookies, or performing unauthorized actions on behalf of users. The vulnerability has a CVSS 3.1 base score of 6.4, reflecting medium severity, with an attack vector of network (remote exploitation), low attack complexity, requiring privileges (Contributor or above), no user interaction, and a scope change affecting confidentiality and integrity but not availability. No public exploits are currently known, but the vulnerability poses a significant risk because Contributor-level access is often granted to trusted users or external content creators. The vulnerability's CWE classification is CWE-79, which covers improper neutralization of input leading to XSS. The issue was published on December 13, 2025, and is tracked by Wordfence and the CVE database. No official patches or updates are currently linked, indicating the need for immediate attention from site administrators.

For European organizations, this vulnerability can lead to unauthorized script execution on WordPress sites using the Custom Frames plugin, potentially resulting in session hijacking, data theft, defacement, or privilege escalation. Since Contributor-level users can exploit this flaw, insider threats or compromised contributor accounts pose a significant risk. The confidentiality and integrity of user data and site content can be compromised, undermining trust and possibly leading to regulatory non-compliance under GDPR if personal data is exposed. The absence of availability impact means service disruption is unlikely, but reputational damage and data breaches remain critical concerns. Organizations relying on WordPress for public-facing or internal sites must consider the risk of attackers injecting malicious scripts that could affect visitors or employees. The medium severity score suggests a moderate but actionable threat, especially in environments with multiple contributors or less stringent access controls.

1. Immediately restrict Contributor-level permissions to trusted users only and review existing Contributor accounts for suspicious activity. 2. Monitor and audit usage of the 'customframe' shortcode and the 'class' parameter for anomalous inputs or unexpected script tags. 3. Apply strict input validation and output encoding on the 'class' parameter if custom development or temporary fixes are possible before an official patch is released. 4. Disable or remove the Custom Frames plugin if it is not essential to reduce the attack surface. 5. Keep WordPress core and all plugins updated, and subscribe to vendor security advisories for prompt patch deployment once available. 6. Employ Web Application Firewalls (WAFs) with rules to detect and block XSS payloads targeting this plugin. 7. Educate contributors about safe content practices and the risks of injecting untrusted code. 8. Conduct regular security scans and penetration tests focusing on plugin vulnerabilities and user privilege misuse.