CVE-2025-3670 in KiwiChat NextClient Plugin
Summary
by MITRE • 05/02/2025
The KiwiChat NextClient plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘url’ parameter in all versions up to, and including, 6.2 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with Contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
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Analysis
by VulDB Data Team • 05/02/2025
The KiwiChat NextClient plugin for WordPress presents a critical stored cross-site scripting vulnerability identified as CVE-2025-3670 affecting all versions through 6.2. This vulnerability stems from inadequate input sanitization and output escaping mechanisms within the plugin's handling of the 'url' parameter. The flaw allows authenticated attackers who possess Contributor-level privileges or higher to inject malicious scripts that persist in the application's database and execute whenever users access affected pages. The vulnerability operates as a stored XSS attack because the malicious code is permanently stored and executed during subsequent page requests rather than requiring immediate interaction with a crafted URL. This type of vulnerability falls under CWE-79 which specifically addresses cross-site scripting flaws in web applications.
The technical exploitation of this vulnerability requires an attacker to have at least Contributor-level access to the WordPress installation, which represents a significant privilege escalation risk since contributors can typically publish posts and comments. The 'url' parameter serves as the attack vector where malicious scripts can be injected into the plugin's processing logic without proper validation or sanitization. When the application retrieves and displays this parameter in web pages, the unescaped content executes in the context of other users' browsers, potentially leading to session hijacking, credential theft, or redirection to malicious sites. The vulnerability's impact extends beyond simple script execution as it can be leveraged for more sophisticated attacks including privilege escalation within the WordPress environment or data exfiltration from authenticated sessions.
The operational impact of this vulnerability creates a persistent threat vector that can affect all users who access pages containing the malicious content. Since the scripts are stored in the database, they continue to execute for any user who visits affected pages regardless of whether the original attacker remains active. This makes the vulnerability particularly dangerous in multi-user environments where contributors might inadvertently create or modify content that includes the malicious payload. The attack can be executed through various means including post creation, comment submission, or any other interface where the 'url' parameter is processed. This stored nature of the vulnerability means that the impact can compound over time as more users access infected pages, potentially leading to widespread compromise of user sessions and data integrity issues.
Organizations should immediately implement mitigation strategies including updating to the latest plugin version if available, applying input validation and output escaping mechanisms, and implementing strict access controls for user roles. The vulnerability demonstrates the critical importance of proper input sanitization and output escaping practices as outlined in OWASP's top ten security risks. Security teams should also consider implementing web application firewalls to detect and block suspicious script injection attempts, along with monitoring user activities for unauthorized content modifications. Regular security audits and vulnerability assessments should be conducted to identify similar issues in other plugins and themes. The ATT&CK framework categorizes this vulnerability under T1059.005 for command and scripting interpreter and T1566.001 for spearphishing attachment, highlighting the potential for further exploitation once initial access is gained through this vulnerability. Additionally, organizations should implement least privilege principles to limit contributor access to only necessary functionality and regularly review user permissions to minimize the attack surface.