CVE-2026-4665 in WP Carousel Free Plugin
Summary
by MITRE • 05/05/2026
The WP Carousel Free plugin for WordPress is vulnerable to Stored Cross-Site Scripting via crafted fancybox `data-caption` attributes in all versions up to, and including, 2.7.10. This is due to the `fancybox-config.js` script reading the carousel container's `id` attribute directly from the DOM to construct a jQuery selector without sanitization. When a Contributor crafts an HTML block with a malformed carousel container ID (containing characters invalid for jQuery selectors), the custom fancybox configuration throws a JavaScript error and fails to initialize. This causes the bundled fancybox library (v3.5.7) to fall back to its default caption handling, which renders the `data-caption` attribute content as raw HTML. Since WordPress allows `data-*` attributes through `wp_kses_post()`, this makes it possible for authenticated attackers, with Contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user clicks an image in the crafted carousel lightbox.
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Analysis
by VulDB Data Team • 06/23/2026
The vulnerability exists within the WP Carousel Free plugin for WordPress, specifically affecting versions up to and including 2.7.10, where a stored cross-site scripting flaw has been identified through crafted fancybox data-caption attributes. This issue stems from the plugin's implementation of the fancybox-config.js script which directly extracts the carousel container's id attribute from the DOM without any sanitization measures. The fundamental technical flaw lies in how the JavaScript code constructs jQuery selectors using this unsanitized id value, creating an attack surface that can be exploited by authenticated users with Contributor-level privileges or higher.
The operational impact of this vulnerability is significant as it allows attackers to inject malicious scripts into carousel lightbox functionality through HTML blocks containing malformed container IDs. When a user with sufficient privileges creates content with invalid jQuery selector characters within the carousel container id, the custom fancybox configuration fails and throws JavaScript errors that cause the library to fall back to default caption handling behavior. This fallback mechanism renders the data-caption attribute content as raw HTML rather than properly sanitizing it, enabling arbitrary script execution when users interact with images in the crafted carousel lightbox.
The security implications extend beyond simple XSS exploitation as this vulnerability leverages WordPress's default content filtering mechanisms that permit data-* attributes through wp_kses_post() function. This means that even though WordPress typically sanitizes content, the specific implementation allows malicious payloads to persist within the data-caption attributes. The attack vector requires an authenticated user with Contributor-level access or higher but can result in persistent script injection across all pages containing vulnerable carousels, making it particularly dangerous for sites with multiple contributors or editorial workflows.
This vulnerability aligns with CWE-79 (Cross-Site Scripting) and follows ATT&CK technique T1566.001 (Phishing via Social Engineering) by enabling attackers to create malicious content that can be executed in victims' browsers when they interact with carousel elements. The issue demonstrates poor input validation and inadequate output sanitization practices, as the plugin fails to properly validate or escape user-provided container IDs before using them in JavaScript context. Organizations should immediately update to patched versions of the WP Carousel Free plugin or implement additional security measures such as restricting Contributor capabilities, implementing stricter content filtering, or deploying web application firewalls to mitigate this risk.
The technical flaw represents a classic case of improper input validation where DOM-based attributes are directly consumed without proper sanitization, creating an environment where malicious inputs can manipulate JavaScript execution contexts. The fallback behavior of the fancybox library when encountering malformed configurations further compounds the vulnerability by providing an unintended execution path for attacker-controlled content. Security teams should monitor for exploitation attempts and consider implementing Content Security Policy headers as additional defense-in-depth measures to limit the impact of successful XSS attacks within their WordPress environments.