CVE-2024-3239 in Post Grid Gutenberg Blocks and Blog Plugin
Summary
by MITRE • 05/14/2024
The Post Grid Gutenberg Blocks and WordPress Blog Plugin WordPress plugin before 4.0.2 does not validate and escape some of its block options before outputting them back in a page/post where the block is embed, which could allow users with the contributor role and above to perform Stored Cross-Site Scripting attacks
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Analysis
by VulDB Data Team • 03/30/2025
The vulnerability identified as CVE-2024-3239 affects the Post Grid Gutenberg Blocks and WordPress Blog Plugin version prior to 4.0.2, representing a critical stored cross-site scripting weakness that undermines web application security. This issue stems from inadequate input validation and output escaping mechanisms within the plugin's block options handling system, creating a persistent security risk that can be exploited by authenticated users. The vulnerability specifically targets the plugin's Gutenberg block implementation where user-provided content is rendered back to pages and posts without proper sanitization, allowing malicious scripts to be stored and executed in the context of other users' browsers.
The technical flaw manifests in the plugin's failure to properly sanitize user inputs when processing block options within the WordPress Gutenberg editor environment. This weakness creates a stored XSS vector because the plugin does not adequately validate or escape data before it is persisted to the database and subsequently rendered back to users viewing the affected content. Attackers with contributor-level privileges or higher can leverage this vulnerability by embedding malicious scripts within block options, which then get executed whenever legitimate users view pages containing these compromised blocks. The vulnerability operates under CWE-79 which categorizes cross-site scripting flaws as weaknesses in input validation and output escaping, specifically targeting the failure to sanitize data before rendering it in web contexts.
The operational impact of CVE-2024-3239 extends beyond simple script execution, as it enables attackers to potentially steal user sessions, deface websites, redirect users to malicious domains, or perform actions on behalf of compromised users. Given that the vulnerability affects users with contributor roles and above, it represents a significant risk to WordPress sites where multiple users have varying permission levels, particularly in environments where content creators and editors have elevated privileges. The stored nature of this vulnerability means that once exploited, malicious payloads persist until manually removed from the database, making it difficult to detect and remediate. This issue aligns with ATT&CK technique T1566.001 which covers phishing with malicious attachments, as attackers could craft malicious block content that appears legitimate to content creators, leading to widespread compromise of user sessions and site integrity.
Mitigation strategies for CVE-2024-3239 require immediate plugin updates to version 4.0.2 or later, which includes proper input validation and output escaping mechanisms. Administrators should implement additional security measures such as role-based access controls, regular security audits, and monitoring for suspicious block content modifications. The WordPress security team recommends that all users upgrade their installations immediately and conduct thorough reviews of existing content to identify and remove any potentially compromised blocks. Organizations should also consider implementing content security policies and regular vulnerability scanning to prevent similar issues from arising in other plugins or themes within their WordPress environments. The fix addresses the core validation issues by implementing proper sanitization of all user inputs before storage and ensuring that output rendering includes appropriate escaping mechanisms to prevent script execution in browser contexts.