CVE-2024-0688 in WebSub Plugin
Summary
by MITRE • 01/25/2024
The "WebSub (FKA. PubSubHubbub)" plugin for WordPress is vulnerable to Stored Cross-Site Scripting via plugin settings in all versions up to, and including, 3.1.4 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with administrator-level permissions 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 • 04/11/2026
The CVE-2024-0688 vulnerability affects the WebSub (formerly PubSubHubbub) plugin for WordPress, representing a critical stored cross-site scripting flaw that has been present in all versions up to and including 3.1.4. This vulnerability resides within the plugin's settings handling mechanism where insufficient input sanitization and output escaping allow malicious actors to inject persistent script code. The flaw specifically targets authenticated administrators who possess sufficient privileges to modify plugin configurations, making it particularly dangerous as it leverages legitimate administrative access to execute malicious payloads. The vulnerability demonstrates a classic weakness in web application security where user-supplied input is not properly validated or escaped before being stored and subsequently rendered in web pages.
The technical exploitation of this vulnerability occurs through the manipulation of plugin settings where administrators can input malicious script code that gets stored in the database. When other users access pages that display these settings or trigger the plugin functionality, the stored scripts execute in their browsers, creating a persistent XSS attack vector. This type of vulnerability falls under CWE-79 - Improper Neutralization of Input During Web Page Generation, which is a fundamental weakness in web application security where input validation and output escaping mechanisms fail to properly sanitize user-provided data. The attack requires only administrative privileges to exploit, making it particularly concerning as it bypasses many standard user access controls and can be leveraged to escalate privileges or steal session cookies from other administrators.
The operational impact of this vulnerability extends beyond simple script execution as it provides attackers with a persistent foothold within the WordPress environment. Once exploited, attackers can perform actions such as modifying content, stealing administrator credentials, accessing sensitive data, or even installing additional malicious plugins to maintain long-term access. The stored nature of the vulnerability means that the malicious scripts remain active until manually removed from the plugin settings, potentially affecting all users who access affected pages. This vulnerability also aligns with ATT&CK technique T1547.001 - Registry Run Keys / Startup Folder, as the persistent nature of stored XSS can be used to establish backdoors or maintain access through browser-based persistence mechanisms. The attack surface is particularly broad given that WordPress administrators frequently modify plugin settings, making this vulnerability likely to be exploited in real-world scenarios.
Mitigation strategies for CVE-2024-0688 should begin with immediate patching of the WebSub plugin to the latest version where the XSS vulnerability has been addressed through proper input sanitization and output escaping mechanisms. Organizations should implement strict access controls and privilege management to limit administrative access to only necessary personnel, as the vulnerability requires administrative-level permissions to exploit. Additionally, security monitoring should be enhanced to detect unusual plugin configuration changes, and regular security audits should be conducted to identify potential malicious modifications. The vulnerability highlights the importance of input validation and output escaping practices as recommended by OWASP Top Ten and other security frameworks. Organizations should also consider implementing Content Security Policy (CSP) headers as an additional defense-in-depth measure to mitigate the impact of potential XSS attacks. Regular security training for administrators on identifying and preventing malicious code injection attempts is also crucial in preventing exploitation of such vulnerabilities.