CVE-2026-2126 in User Submitted Posts Plugin
Summary
by MITRE • 02/18/2026
The User Submitted Posts – Enable Users to Submit Posts from the Front End plugin for WordPress is vulnerable to Incorrect Authorization in all versions up to, and including, 20260113. This is due to the `usp_get_submitted_category()` function accepting user-submitted category IDs from the POST body without validating them against the admin-configured allowed categories stored in `usp_options['categories']`. This makes it possible for unauthenticated attackers to assign submitted posts to arbitrary categories, including restricted ones, by crafting a direct POST request with manipulated `user-submitted-category[]` values, bypassing the frontend category restrictions.
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Analysis
by VulDB Data Team • 02/18/2026
The vulnerability identified in CVE-2026-2126 affects the User Submitted Posts plugin for WordPress, a widely used tool that enables front-end post submission capabilities. This particular flaw represents a critical authorization bypass issue that undermines the security controls designed to restrict category assignment permissions. The vulnerability exists in all versions up to and including 20260113, making it a persistent threat across multiple plugin releases. The core issue stems from insufficient input validation within the plugin's category handling mechanism, which fails to properly verify user-submitted data against established administrative configurations.
The technical flaw manifests through the `usp_get_submitted_category()` function which processes category assignments without performing proper authorization checks. This function directly accepts category IDs from the POST request body without cross-referencing them against the legitimate categories configured by administrators in the `usp_options['categories']` setting. The vulnerability creates a direct path for attackers to manipulate category assignments by crafting malicious POST requests that include modified `user-submitted-category[]` parameters. This allows unauthorized users to bypass the intended frontend category restrictions and assign posts to categories that should be restricted or inaccessible to regular users.
The operational impact of this vulnerability extends beyond simple category assignment manipulation and represents a significant threat to content management integrity. Attackers can exploit this flaw to publish content under restricted categories, potentially gaining access to sensitive areas of a website's content structure or bypassing content moderation controls. This authorization bypass could enable malicious actors to post content in categories that are typically reserved for administrators or specific user groups, undermining the hierarchical content management system. The vulnerability is particularly dangerous because it operates without requiring authentication, allowing unauthenticated attackers to manipulate the content structure directly through API endpoints.
Security implications of this vulnerability align with CWE-284, which addresses improper access control in software systems, and can be mapped to ATT&CK technique T1078 for valid accounts and T1566 for social engineering through malicious content manipulation. The vulnerability creates opportunities for attackers to perform content poisoning, manipulate website navigation structures, or gain unauthorized access to restricted content areas through category-based access controls. Organizations using this plugin face risks of reputational damage, content integrity compromise, and potential information disclosure through unauthorized category access. The attack vector is straightforward and requires minimal technical expertise to exploit, making it particularly dangerous in environments where content moderation and access control are critical security considerations.
Mitigation strategies should focus on immediate plugin updates to versions that address the authorization bypass, along with implementing additional security controls such as input validation at multiple layers and monitoring for unauthorized category assignments. Administrators should also consider implementing web application firewalls to detect and block suspicious POST requests containing malformed category parameters. Regular security audits of plugin configurations and access controls are essential to prevent exploitation of similar authorization bypass vulnerabilities. The recommended approach involves applying the vendor-provided security patches, conducting thorough security assessments of the affected plugin's functionality, and implementing proper access control measures that validate all user-submitted category data against established administrative configurations.