CVE-2026-4431 in Easy Post Submission Plugin
Summary
by MITRE • 08/05/2026
The Easy Post Submission plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the `create_post()` function in all versions up to, and including, 2.3.0. This is due to the `rbsm_submit_post` AJAX action being registered for unauthenticated users via `wp_ajax_nopriv_rbsm_submit_post` without any authorization checks when a `postId` parameter is supplied. This makes it possible for unauthenticated attackers to modify the title, content, excerpt, categories, and tags of arbitrary posts, as well as change the post status to draft (effectively unpublishing them) via the 'postId' parameter.
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Analysis
by VulDB Data Team • 08/05/2026
The Easy Post Submission plugin for WordPress presents a critical authorization vulnerability that undermines the integrity of content management operations. This flaw exists in all versions up to and including 2.3.0, creating a pathway for unauthorized users to manipulate published content without proper authentication credentials. The vulnerability stems from improper capability validation within the plugin's core functionality, specifically affecting the create_post() function implementation.
The technical mechanism behind this vulnerability involves the registration of the rbsm_submit_post AJAX action through wp_ajax_nopriv_rbsm_submit_post hook, which explicitly allows unauthenticated access to the endpoint. When attackers supply a postId parameter to this action, no authorization checks are performed to verify whether the requesting user has sufficient privileges to modify the targeted post. This design flaw enables arbitrary post modification operations regardless of the user's authentication status or role permissions.
The operational impact of this vulnerability extends beyond simple content tampering to encompass complete post lifecycle manipulation. Attackers can alter fundamental post attributes including title, content, excerpt, categories, and tags, effectively rewriting published material. Additionally, the vulnerability permits changing post status to draft, which serves as an effective unpublishing mechanism that removes content from public visibility. This capability allows attackers to not only modify existing posts but also to remove them entirely from audience access.
From a cybersecurity perspective, this vulnerability maps directly to CWE-863 (Incorrect Authorization) and aligns with ATT&CK technique T1078 (Valid Accounts) as it exploits the absence of proper access controls rather than requiring stolen credentials. The flaw represents a classic case of insufficient privilege checking in web applications, where the system fails to verify that the requesting entity has appropriate authorization levels for the requested operations. This vulnerability type falls under the broader category of insecure direct object references, where attackers can directly manipulate objects through parameter manipulation without proper authorization validation.
Mitigation strategies should focus on implementing proper capability checks within the plugin's AJAX handling code. The recommended approach involves adding authentication verification before processing any post modification requests, ensuring that only authenticated users with appropriate permissions can modify existing posts. Additionally, developers should implement input validation for the postId parameter and establish proper access control lists that verify user privileges against specific post objects. Organizations should also consider immediate plugin updates or removal if patching is not feasible, while monitoring for suspicious activity in their WordPress installations that might indicate exploitation attempts.
The vulnerability demonstrates how seemingly minor implementation oversights can create significant security risks in content management systems. The absence of proper authorization controls creates an attack surface that allows adversaries to manipulate published content without detection, potentially leading to reputation damage, information disclosure, or malicious content injection. Security practitioners should prioritize identifying and remediating similar authorization flaws across all WordPress plugins and themes, as these vulnerabilities often remain undetected for extended periods due to their subtle nature and the complexity of modern web application architectures.