CVE-2026-4120 in Info Cards Plugin
Summary
by MITRE • 03/19/2026
The Info Cards – Add Text and Media in Card Layouts plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'btnUrl' parameter within the Info Cards block in all versions up to, and including, 2.0.7. This is due to insufficient input validation on URL schemes, specifically the lack of javascript: protocol filtering. The block's render.php passes all attributes as JSON to the frontend via a data-attributes HTML attribute using esc_attr(wp_json_encode()), which prevents HTML attribute injection but does not validate URL protocols within the JSON data. The client-side view.js then renders the btnUrl value directly as an href attribute on anchor elements without any protocol sanitization. This makes it possible for authenticated attackers, with Contributor-level access and above, to inject javascript: URLs that execute arbitrary web scripts when a user clicks the rendered button link.
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Analysis
by VulDB Data Team • 03/19/2026
The vulnerability identified as CVE-2026-4120 affects the Info Cards WordPress plugin, specifically targeting versions up to and including 2.0.7. This represents a critical stored cross-site scripting flaw that exploits the plugin's handling of URL parameters within its Info Cards block functionality. The vulnerability stems from inadequate input validation mechanisms that fail to properly sanitize URL schemes, creating an attack vector that can be exploited by authenticated users with Contributor-level permissions or higher. The security implications are particularly concerning given that this allows attackers to inject malicious javascript: URLs that execute arbitrary code when users interact with the compromised plugin functionality.
The technical flaw manifests in the plugin's data handling architecture where the block's render.php file processes all attributes by encoding them as JSON and passing them to the frontend through data-attributes HTML attributes using esc_attr(wp_json_encode()). While this approach prevents traditional HTML attribute injection attacks through proper escaping, it fails to implement protocol validation within the JSON data itself. The vulnerability becomes apparent when the client-side view.js component processes the btnUrl value by directly inserting it into anchor element href attributes without any sanitization of the URL protocol. This direct insertion pattern creates a pathway for malicious javascript: URLs to be executed within the context of a user's browser session, effectively bypassing standard HTML sanitization measures.
The operational impact of this vulnerability extends beyond simple script execution, as it enables attackers to perform a wide range of malicious activities including session hijacking, data exfiltration, and redirection to malicious sites. Since the vulnerability requires only Contributor-level access, it represents a significant risk to WordPress installations where multiple users have varying permission levels. The stored nature of the vulnerability means that once an attacker successfully injects malicious code, it persists until manually removed, potentially affecting all users who view the compromised content. This makes the vulnerability particularly dangerous in collaborative environments where content creators might not be security-aware and could inadvertently introduce malicious payloads through legitimate editing activities.
The vulnerability aligns with CWE-79, which describes Cross-Site Scripting flaws, and demonstrates characteristics consistent with ATT&CK technique T1566.001, which involves the use of malicious content delivery through web applications. Organizations should prioritize immediate remediation by updating to the latest version of the plugin where this vulnerability has been addressed. Additionally, administrators should implement network-level monitoring to detect suspicious URL patterns and consider implementing content security policies to mitigate the impact of potential exploitation. The incident highlights the critical importance of validating all user-supplied input, particularly URL schemes, and demonstrates that even well-intentioned security measures like esc_attr() can be insufficient when protocol validation is missing from the overall security architecture.