CVE-2025-3516 in Simple Lightbox Plugin
Summary
by MITRE • 05/16/2025
The Simple Lightbox WordPress plugin before 2.9.4 does not validate and escape some of its attributes before outputting them back in a page/post, which could allow users with the contributor role and above to perform Stored Cross-Site Scripting attacks.
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Analysis
by VulDB Data Team • 05/16/2025
The Simple Lightbox WordPress plugin vulnerability CVE-2025-3516 represents a critical stored cross-site scripting flaw that affects versions prior to 2.9.4. This vulnerability resides in the plugin's failure to properly validate and escape user-supplied attributes before rendering them in web pages or posts. The issue specifically impacts users with the contributor role and above, indicating that even relatively low-privileged WordPress users can exploit this weakness to inject malicious scripts into the application's output. The vulnerability stems from inadequate input sanitization practices within the plugin's attribute handling mechanisms, creating an attack surface where malicious payloads can be persisted and executed whenever affected content is rendered.
The technical implementation of this vulnerability demonstrates a classic stored XSS pattern where user input flows directly into the plugin's output generation without proper sanitization. When contributors or higher-privileged users create or modify content that utilizes the Simple Lightbox plugin functionality, they can inject malicious JavaScript code through attributes that are subsequently stored in the database. This stored payload becomes active whenever the affected page or post is viewed by other users, making it particularly dangerous as it can propagate across multiple users without requiring additional interaction from the target. The vulnerability's impact extends beyond simple script execution as it can potentially enable attackers to steal session cookies, perform unauthorized actions on behalf of users, or redirect victims to malicious sites.
From an operational perspective, this vulnerability presents significant risk to WordPress installations relying on the Simple Lightbox plugin, particularly those with multiple contributors or users who can create content. The low privilege requirement means that even users with minimal administrative rights can potentially compromise the entire site's security. The stored nature of the vulnerability ensures that the malicious code persists until manually removed or the plugin is updated, creating a long-term threat vector. Attackers can leverage this vulnerability to establish persistent access patterns, harvest user credentials, or deploy additional malware within the compromised WordPress environment. The vulnerability's presence in a widely-used plugin increases the likelihood of exploitation across multiple sites, making it a preferred target for automated attacks.
Security mitigations for CVE-2025-3516 primarily focus on immediate remediation through plugin updates to version 2.9.4 or later, which contain the necessary validation and sanitization fixes. Organizations should implement comprehensive input validation across all user-supplied data within WordPress installations, ensuring that all attributes passed to plugins undergo proper sanitization before being rendered. The vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws, and represents a failure in output encoding and input validation practices. From an ATT&CK framework perspective, this vulnerability maps to techniques involving command and control communication, credential access, and persistence mechanisms. Administrators should also consider implementing web application firewalls to detect and block suspicious script payloads, conduct regular security audits of installed plugins, and maintain up-to-date security monitoring systems to detect potential exploitation attempts. Additionally, role-based access controls should be reviewed to minimize the potential impact of compromised accounts, and users should be educated about the risks of injecting unknown code into content management systems.