CVE-2025-5533 in Knowledge Base Plugin
Summary
by MITRE • 06/06/2025
The Knowledge Base plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's 'kbalert' shortcode in all versions up to, and including, 2.3.0 due to insufficient input sanitization and output escaping on user supplied attributes. 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 • 06/06/2025
The vulnerability identified as CVE-2025-5533 affects the Knowledge Base plugin for WordPress, specifically targeting versions up to and including 2.3.0. This represents a critical security flaw that undermines the integrity of WordPress installations relying on this plugin for knowledge base functionality. The vulnerability manifests through the plugin's 'kbalert' shortcode implementation, which fails to properly sanitize or escape user-supplied input parameters. Security researchers have classified this issue as a stored cross-site scripting vulnerability, indicating that malicious payloads can be permanently stored within the application's database and subsequently executed whenever affected pages are accessed by unsuspecting users.
The technical exploitation of this vulnerability requires an attacker to possess contributor-level access or higher within the WordPress environment, which significantly reduces the attack surface but does not eliminate the risk entirely. The flaw stems from inadequate input validation mechanisms that fail to properly sanitize attributes passed to the 'kbalert' shortcode, combined with insufficient output escaping during the rendering process. This dual failure creates an environment where malicious scripts can be injected and stored within the plugin's data structures, making the vulnerability persistent across multiple user sessions and page views. The vulnerability directly maps to CWE-79 which specifically addresses cross-site scripting flaws, and aligns with ATT&CK technique T1566.001 which covers spearphishing via web applications.
The operational impact of this vulnerability extends beyond simple data theft or defacement, as it enables attackers to execute arbitrary code within the context of affected users' browsers. This capability allows for session hijacking, credential theft, and the potential installation of malware or backdoors on victim systems. The stored nature of the vulnerability means that even users who do not actively visit the compromised pages may be exposed to attacks when their browsers load cached content or when administrators view pages containing malicious scripts. The vulnerability affects all users who have access to pages containing the kbalert shortcode, potentially exposing administrators, editors, and contributors to persistent threats that can be leveraged for broader network infiltration.
Mitigation strategies should prioritize immediate patching of the Knowledge Base plugin to the latest version that addresses this vulnerability. Organizations should implement strict access controls and monitor user activities for suspicious behavior that might indicate exploitation attempts. Security teams should consider implementing content security policies that restrict script execution within the WordPress environment, and establish regular vulnerability scanning procedures to identify similar issues in other plugins or themes. Additionally, administrators should educate users about the risks of visiting untrusted pages and the importance of maintaining updated software versions to prevent exploitation of known vulnerabilities. The remediation process should also include thorough audit of existing content for potential malicious scripts and implementation of proper input validation and output escaping mechanisms throughout the application's codebase.