CVE-2024-12026 is a vulnerability identified in the Message Filter for Contact Form 7 plugin for WordPress, developed by kofimokome. The flaw is due to a missing authorization (CWE-862) in the saveFilter() function, which is responsible for saving message filters within the plugin. This missing capability check means that any authenticated user with Subscriber-level access or higher can create new filters without proper permission validation. Since Subscribers are typically low-privilege users, this vulnerability allows unauthorized modification of plugin data, potentially enabling attackers to manipulate how messages are filtered or processed by the Contact Form 7 plugin. The vulnerability affects all versions up to and including 1.6.3. The CVSS 3.1 base score is 4.3 (medium), with vector AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N, indicating network attack vector, low attack complexity, low privileges required, no user interaction, unchanged scope, no confidentiality or availability impact, but limited integrity impact. No patches or exploits are currently reported, but the vulnerability is publicly disclosed as of December 7, 2024. This issue is significant because Contact Form 7 is a widely used WordPress plugin, and the Message Filter extension is used to customize form message handling. Unauthorized filter creation could be leveraged to bypass intended filtering rules or introduce malicious filtering behavior.

The primary impact of CVE-2024-12026 is unauthorized modification of message filtering rules within the Contact Form 7 plugin environment. While it does not directly compromise confidentiality or availability, it undermines the integrity of form message processing. Attackers with Subscriber-level access can create filters that may alter or bypass intended filtering logic, potentially allowing spam, malicious content, or unwanted messages to be processed or delivered. This could degrade the reliability of contact forms, facilitate social engineering or phishing attacks, or enable further exploitation by manipulating form data handling. Since the vulnerability requires only low-level authenticated access, it increases the risk from insider threats or compromised low-privilege accounts. Organizations relying on Contact Form 7 with the Message Filter plugin may face reputational damage, increased spam, or indirect security risks if attackers exploit this flaw to manipulate form submissions or evade detection mechanisms.

To mitigate CVE-2024-12026, organizations should first verify if they use the Message Filter for Contact Form 7 plugin and identify the installed version. Since no official patch is currently available, administrators should consider the following specific actions: 1) Restrict Subscriber-level user creation and monitor existing low-privilege accounts to reduce the risk of exploitation. 2) Implement custom capability checks or hooks in WordPress to enforce authorization on the saveFilter() function, ensuring only trusted roles (e.g., Administrator or Editor) can create or modify filters. 3) Employ web application firewalls (WAFs) with rules to detect and block unauthorized POST requests targeting the filter creation endpoints. 4) Monitor plugin logs and WordPress audit trails for unusual filter creation activity or changes in message filtering behavior. 5) Educate site administrators about the risk and encourage prompt updates once an official patch is released. 6) Consider temporarily disabling the Message Filter plugin if the risk outweighs its benefits until a fix is available. These targeted mitigations go beyond generic advice by focusing on access control hardening and monitoring specific to this vulnerability.