CVE-2026-96524 in MCP Server Plugin
Summary
by MITRE • 09/26/2026
The MCP Server for WordPress WordPress plugin before 1.8.2 does not correctly verify the WordPress REST API nonce for cookie-authenticated requests when a condition an attacker can influence is present, allowing unauthenticated attackers to perform administrator-only actions, including creating a new administrator account, by tricking a logged-in administrator into visiting a crafted page.
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Analysis
by VulDB Data Team • 09/26/2026
The vulnerability identified in versions of the MCP Server for WordPress plugin prior to 1.8.2 represents a critical failure in access control mechanisms, specifically within the handling of cookie-authenticated requests against the WordPress REST API. This flaw stems from an improper verification process regarding nonces, which are unique tokens used by WordPress to prevent Cross-Site Request Forgery attacks and ensure that state-changing actions originate from legitimate user interactions rather than malicious third-party sites. In a secure implementation, every sensitive request must carry a valid nonce generated specifically for the current session and action type. However, in this affected version of the plugin, the verification logic contains a conditional bypass where certain input parameters or environmental conditions allow an attacker to circumvent these checks entirely. This architectural weakness effectively neutralizes one of WordPress's primary defenses against unauthorized state changes, leaving administrators exposed when they interact with compromised content while logged into their dashboard.
The operational impact of this vulnerability is severe due to its potential for privilege escalation through social engineering tactics such as cross-site request forgery. An attacker does not need valid credentials or prior authentication themselves; instead, the exploit relies on tricking a currently authenticated administrator into visiting a maliciously crafted webpage. When an administrator with active session cookies visits this page, their browser automatically includes those cookies in any requests made to the WordPress site, including API calls triggered by scripts embedded within the attacker's page. Because the plugin fails to properly validate the nonce under specific influenced conditions, these forged requests are accepted as legitimate administrative actions. Consequently, an unauthenticated remote actor can execute high-privilege operations without detection or consent from the victim user session holder.
The most critical consequence of this flaw is the ability for attackers to create new administrator accounts on the targeted WordPress installation. By exploiting the lack of proper nonce verification, a malicious party can send REST API requests that add a new user with full administrative privileges. Once created, these backdoor accounts provide persistent access to the system, allowing the attacker to modify site content, install additional malware, exfiltrate sensitive data, or further compromise the underlying server infrastructure. This scenario transforms a simple web vulnerability into a complete system takeover vector, as gaining administrator control over WordPress typically grants significant leverage over the associated database and potentially the hosting environment depending on configuration settings.
From a classification perspective, this issue aligns with CWE-352, which describes Cross-Site Request Forgery vulnerabilities where an application fails to verify that requests originate from trusted sources. Furthermore, it relates closely to CWE-862 regarding missing authorization checks, as the system permits actions reserved for privileged users without adequate proof of intent or session validity. In terms of offensive security frameworks like MITRE ATT&CK, this vulnerability facilitates techniques associated with Account Manipulation and Privilege Escalation, specifically under tactics that involve gaining initial access through social engineering followed by lateral movement via compromised credentials. The specific mechanism of using a crafted page to trigger actions in an authenticated session is characteristic of CSRF-based exploitation patterns often seen in web application attacks targeting content management systems.
Mitigation strategies must prioritize immediate patching and defensive coding practices. Administrators running affected versions should upgrade the MCP Server for WordPress plugin to version 1.8.2 or later, where the nonce verification logic has been corrected to properly validate all cookie-authenticated requests regardless of external conditions. For organizations unable to update immediately due to compatibility constraints, implementing additional security layers is essential. This includes deploying Web Application Firewalls configured to detect and block anomalous REST API patterns indicative of CSRF attacks, such as sudden spikes in administrative endpoint calls from unfamiliar user agents or IP addresses. Additionally, enforcing strict Content Security Policy headers can help mitigate the risk by restricting script execution contexts, thereby reducing the effectiveness of crafted pages attempting to trigger unauthorized actions. Regular security audits focusing on authentication token handling and REST API implementation standards are also recommended to prevent similar vulnerabilities in custom code or other plugins within the ecosystem.