CVE-2026-2594 in Smart Custom Fields Plugin
Summary
by MITRE • 07/17/2026
The Smart Custom Fields plugin for WordPress is vulnerable to Stored Cross-Site Scripting in versions up to, and including, 5.0.7. This is due to insufficient input sanitization and output escaping of uploaded image attachment titles. This makes it possible for authenticated attackers, with Author-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. NOTE: This vulnerability was partially patched in 5.0.7.
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Analysis
by VulDB Data Team • 07/17/2026
The Smart Custom Fields plugin for WordPress represents a significant security weakness that has persisted through multiple versions up to 5.0.7, creating a persistent threat vector for malicious actors within WordPress environments. This vulnerability specifically targets the plugin's handling of uploaded image attachment titles, where inadequate input sanitization and output escaping mechanisms leave the system exposed to stored cross-site scripting attacks. The flaw affects authenticated users who possess at least Author-level privileges, making it particularly dangerous in environments where content creators or editors might be compromised, as these attackers can leverage their legitimate access rights to execute malicious code across the entire WordPress installation.
The technical nature of this vulnerability stems from the plugin's failure to properly sanitize user-supplied data when processing image attachment titles. When users upload images through the Smart Custom Fields interface, the plugin stores these title values without adequate filtering or escaping mechanisms. This creates a classic stored XSS scenario where malicious scripts can be injected into the system and remain persistent until manually removed. The vulnerability operates at the intersection of input validation and output encoding, where CWE-79 Cross-Site Scripting occurs due to insufficient sanitization of user-controllable data within the plugin's image handling functionality. Attackers can craft specially formatted titles that contain malicious JavaScript code, which then gets executed whenever any user accesses pages containing these compromised attachment titles.
The operational impact of this vulnerability extends far beyond simple script execution, as it provides attackers with a persistent foothold within WordPress environments where they have Author-level access or higher. Once exploited, the malicious scripts can perform various harmful activities including but not limited to cookie theft, session hijacking, redirection to malicious sites, and potentially full administrative compromise of the affected WordPress installation. The stored nature of the vulnerability means that even if the initial injection occurs during a brief period when an attacker has access, the malicious code continues to execute whenever any user views pages containing the compromised content, creating an ongoing threat vector that can persist long after the initial attack window has closed. This characteristic aligns with ATT&CK technique T1566.001 for initial access through malicious attachments and T1059.001 for command and scripting interpreter.
Organizations running vulnerable versions of Smart Custom Fields must implement immediate mitigations to protect their WordPress installations from exploitation attempts. The most effective approach involves updating to the latest plugin version where this vulnerability has been addressed, though it's important to note that version 5.0.7 contained only partial patching, meaning additional verification may be required. Administrators should also implement additional security measures including role-based access controls, regular monitoring of user activity, and input validation for all user-uploaded content. The vulnerability demonstrates the critical importance of proper sanitization practices in web applications, particularly when handling user-controllable data that gets stored and later rendered in web pages. Security teams should conduct thorough penetration testing and vulnerability assessments to identify any other potential injection points within their WordPress environments, as this vulnerability serves as a reminder of the pervasive nature of XSS threats in content management systems where user-generated content processing is involved.