CVE-2025-3750 in Network Posts Extended Plugin
Summary
by MITRE • 05/21/2025
The Network Posts Extended plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘post_height’ parameter in all versions up to, and including, 7.7.1 due to insufficient input sanitization and output escaping. 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 accesses an injected page.
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Analysis
by VulDB Data Team • 05/26/2026
The Network Posts Extended plugin for WordPress represents a critical security vulnerability that affects versions up to and including 7.7.1, exposing WordPress installations to stored cross-site scripting attacks through the 'post_height' parameter. This vulnerability resides within the plugin's handling of user input and demonstrates a fundamental failure in input validation and output sanitization practices that directly impacts the security posture of affected websites. The flaw specifically targets authenticated users who possess contributor-level access or higher privileges, making it particularly concerning as it allows attackers to leverage existing user permissions to execute malicious code within the context of the target website.
The technical implementation of this vulnerability stems from insufficient input sanitization mechanisms that fail to properly validate or escape the 'post_height' parameter before storing user-provided data in the database. When administrators or contributors modify post settings through the plugin interface, the input value is not adequately filtered to remove or escape potentially malicious script content. This stored data then gets rendered in subsequent page views without proper output escaping, creating an environment where arbitrary web scripts can be executed whenever any user accesses pages containing the injected content. The vulnerability classifies under CWE-79 which specifically addresses cross-site scripting flaws, and represents a classic case of stored XSS where malicious payloads persist in the application's data store rather than being reflected in HTTP responses.
The operational impact of this vulnerability extends beyond simple script execution, as authenticated attackers with contributor privileges can potentially escalate their access or cause significant damage to the affected WordPress installation. The stored nature of the XSS payload means that any user who accesses pages containing the malicious content becomes a potential vector for further attacks, including session hijacking, credential theft, or redirection to malicious sites. Attackers could craft sophisticated payloads that target administrator accounts, potentially leading to full site compromise through privilege escalation. The vulnerability also aligns with ATT&CK technique T1566.001 which covers the exploitation of web applications through cross-site scripting, demonstrating how seemingly minor input validation flaws can create substantial security risks in content management systems.
Organizations using the Network Posts Extended plugin must implement immediate mitigation strategies to protect their WordPress installations from exploitation. The primary recommendation involves upgrading to the latest version of the plugin where the vulnerability has been patched, as the developers have addressed the insufficient input sanitization and output escaping issues. Additionally, administrators should consider implementing web application firewalls that can detect and block malicious script injection attempts, while also monitoring user activities for suspicious modifications to post parameters. Role-based access controls should be reviewed to ensure that only trusted users have contributor-level access or higher, as this reduces the attack surface for exploitation. Regular security audits of WordPress plugins and themes should be conducted to identify and remediate similar vulnerabilities, with particular attention to input validation and output escaping mechanisms. The vulnerability serves as a reminder of the critical importance of proper sanitization practices in web applications and the necessity of following security best practices such as those outlined in the OWASP Top Ten project to prevent common web application vulnerabilities.