CVE-2026-1275 Overview
The Multi Post Carousel by Category plugin for WordPress contains a Stored Cross-Site Scripting (XSS) vulnerability in the slides shortcode attribute across all versions up to and including version 1.4. The vulnerability stems from insufficient input sanitization and output escaping on the user-supplied slides parameter within the post_slides_shortcode function. Authenticated attackers with Contributor-level access or higher can exploit this flaw to inject arbitrary web scripts into pages, which execute whenever a user accesses the compromised page.
Critical Impact
Authenticated attackers can inject persistent malicious scripts that execute in the context of other users' sessions, potentially leading to session hijacking, credential theft, or further site compromise.
Affected Products
- Multi Post Carousel by Category plugin for WordPress version 1.4 and earlier
Discovery Timeline
- 2026-03-21 - CVE CVE-2026-1275 published to NVD
- 2026-03-23 - Last updated in NVD database
Technical Details for CVE-2026-1275
Vulnerability Analysis
This Stored Cross-Site Scripting (XSS) vulnerability exists in the shortcode processing functionality of the Multi Post Carousel by Category WordPress plugin. The vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation).
The flaw occurs because the post_slides_shortcode function does not properly sanitize or escape the slides parameter before rendering it in the page output. When a user with Contributor-level privileges or higher creates or edits content using the vulnerable shortcode, they can embed malicious JavaScript that persists in the WordPress database and executes in the browsers of any visitor who views the affected page.
The network-based attack vector with low complexity makes this vulnerability relatively straightforward to exploit for attackers who have obtained even minimal authenticated access to the WordPress installation. The scope change characteristic indicates that the vulnerability can affect resources beyond the vulnerable component's security scope.
Root Cause
The root cause is the lack of proper input validation and output encoding in the post_slides_shortcode function located at line 174 of multi-post-carousel.php. The plugin fails to sanitize user-controlled input before incorporating it into the rendered HTML output, violating secure coding practices for WordPress plugin development.
WordPress provides built-in escaping functions such as esc_attr(), esc_html(), and wp_kses() specifically designed to prevent XSS attacks, but these functions are not properly applied to the slides shortcode attribute before output.
Attack Vector
The attack leverages the WordPress shortcode system to deliver the malicious payload. An attacker with at minimum Contributor-level access can craft a malicious shortcode containing JavaScript code in the slides attribute. When saved, the malicious content is stored in the WordPress database and subsequently rendered without proper escaping to any visitor accessing the page.
The vulnerability does not require any user interaction beyond normal page access, and the injected scripts execute automatically when the page loads. This makes it effective for attacks targeting site administrators, editors, or general visitors.
Detection Methods for CVE-2026-1275
Indicators of Compromise
- Presence of unexpected JavaScript code or HTML tags within post content using the Multi Post Carousel shortcode
- Unusual slides attribute values in shortcode usage containing script tags, event handlers, or encoded payloads
- Reports from users experiencing unexpected behavior such as redirects or pop-ups when viewing carousel pages
Detection Strategies
- Review WordPress posts and pages containing [post_slides] or [multi_post_carousel] shortcodes for malicious payloads in the slides attribute
- Implement Content Security Policy (CSP) headers to detect and block inline script execution attempts
- Deploy Web Application Firewall (WAF) rules to flag suspicious patterns in shortcode attributes
Monitoring Recommendations
- Monitor WordPress audit logs for content modifications by Contributor-level users, particularly those affecting shortcode usage
- Enable SentinelOne's behavioral detection for anomalous JavaScript execution patterns on WordPress sites
- Implement file integrity monitoring on the multi-post-carousel.php plugin file to detect unauthorized modifications
How to Mitigate CVE-2026-1275
Immediate Actions Required
- Update the Multi Post Carousel by Category plugin to the latest patched version as soon as one becomes available
- Review and remove any suspicious content from posts using the affected shortcode
- Temporarily restrict Contributor and Author user roles from editing posts with the vulnerable shortcode
- Audit user accounts with Contributor-level access or higher for unauthorized accounts
Patch Information
The vulnerable code is located at line 174 in multi-post-carousel.php. Organizations should monitor the WordPress Plugin Repository for an updated version that addresses this vulnerability. The Wordfence Vulnerability Report provides additional tracking information.
Workarounds
- Deactivate the Multi Post Carousel by Category plugin until a security patch is available
- Implement a Web Application Firewall rule to filter malicious input patterns in shortcode attributes
- Restrict the ability to use shortcodes to trusted Administrator accounts only by implementing custom capability checks
If patching is not immediately possible, consider adding manual input sanitization by modifying the plugin's shortcode handler to escape the slides parameter using WordPress's esc_attr() function before output. Note that modifying plugin code directly may be overwritten by future updates and should only be a temporary measure.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
