MountDev AI MCP Connector WordPress Plugin Vulnerability Allows Unauthenticated Admin Access (CVE-2026-15015)

CVE-2026-15015 describes a critical authorization bypass vulnerability affecting all versions up to, and including, 1.6.1 of the MountDev AI MCP Connector for WordPress plugin. This flaw stems from inadequate verification of user authorization, enabling unauthenticated attackers to acquire an administrator-level OAuth Bearer token. Attackers can leverage a publicly accessible Dynamic Client Registration endpoint to register arbitrary OAuth clients with a controlled redirect_uri, then utilize an unprotected authorization endpoint to complete the OAuth flow without requiring any administrator interaction. This leads to full administrator-equivalent control over the plugin's MCP tool surface and, by extension, all exposed WordPress content, user data, and configuration options. The vulnerability carries a CVSS v3.1 Base Score of 9.8, indicating severe impact and ease of exploitation for any affected WordPress site.

Attack Chain

1. An unauthenticated attacker identifies a WordPress instance running the MountDev AI MCP Connector plugin.
2. The attacker accesses the publicly exposed Dynamic Client Registration endpoint provided by the plugin.
3. The attacker registers an arbitrary OAuth client by providing a malicious redirect_uri that they control.
4. The attacker then initiates an OAuth authorization request using the newly registered client, leveraging an unprotected authorization endpoint within the plugin.
5. The plugin processes the OAuth flow, completing it without requiring any legitimate administrator interaction or approval.
6. Upon successful completion of the OAuth flow, the attacker obtains a valid OAuth Bearer token.
7. This token is administrator-bound, granting the attacker full administrator-equivalent access to the plugin's MCP tool surface.
8. The attacker uses this access to modify or exfiltrate WordPress content, user data, and system options.

Impact

A successful exploitation of CVE-2026-15015 grants unauthenticated attackers full administrative control over the affected WordPress installation via the MountDev AI MCP Connector. This allows for complete compromise of the website, including unauthorized access to sensitive data, modification or defacement of content, creation of new administrative users, and potential injection of malicious code. The high CVSS score of 9.8 reflects the ease of exploitation and the devastating consequences, posing a severe risk to data integrity, confidentiality, and availability for organizations utilizing the vulnerable plugin.

Recommendation

• Immediately update the MountDev AI MCP Connector for WordPress plugin to a version patched against CVE-2026-15015.
• Deploy the provided Sigma rule to your SIEM to detect attempts at exploiting the Dynamic Client Registration endpoint.
• Review web server access logs for unusual POST requests to /wp-json/mountdev-ai-mcp-connector/v1/client/register or similar endpoints, particularly those containing suspicious redirect_uri parameters.