CVE-2026-11366 in MonsterInsights Plugin
Summary
by MITRE • 08/04/2026
The MonsterInsights WordPress plugin before 11.1.0 does not correctly validate the signature on one of its unauthenticated AJAX actions: when the MonsterInsights WordPress plugin before 11.1.0 is not connected to Google Analytics the HMAC signing key is empty, which lets unauthenticated attackers forge a valid signature and overwrite a MonsterInsights WordPress plugin before 11.1.0 configuration value, disrupting the MonsterInsights WordPress plugin before 11.1.0's server-side analytics in Manual GA4 mode.
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Analysis
by VulDB Data Team • 08/04/2026
The vulnerability in MonsterInsights WordPress plugin versions prior to 11.1.0 represents a critical authentication bypass flaw that undermines the plugin's security model and exposes core functionality to unauthorized manipulation. This weakness stems from inadequate signature validation mechanisms within one of the plugin's unauthenticated AJAX endpoints, specifically when the plugin operates in Manual GA4 mode without Google Analytics connectivity. The issue creates a pathway for attackers to exploit the absence of proper cryptographic verification, effectively allowing them to craft malicious requests that appear legitimate to the system's security checks.
The technical flaw manifests through the plugin's handling of HMAC signatures when no valid Google Analytics connection exists. In normal operation, the plugin would utilize a cryptographic key to sign AJAX requests and verify their authenticity before processing any configuration changes. However, when the MonsterInsights plugin is not connected to Google Analytics, it fails to properly initialize or validate the HMAC signing key, leaving the signature verification process vulnerable to manipulation. This occurs because the system defaults to an empty signing key in the absence of a Google Analytics connection, which fundamentally breaks the cryptographic integrity checks that should prevent unauthorized modifications.
The operational impact of this vulnerability extends beyond simple configuration tampering, as it can severely disrupt the plugin's core analytics functionality and potentially compromise the entire WordPress site's tracking capabilities. Attackers who exploit this flaw can overwrite critical MonsterInsights configuration values, effectively breaking the server-side analytics processing that the plugin relies upon for data collection and reporting. This disruption becomes particularly problematic in Manual GA4 mode where the plugin operates independently of standard Google Analytics integration patterns, making the system more susceptible to manipulation through forged requests.
This vulnerability aligns with CWE-347, which addresses improper verification of cryptographic signatures, and represents a direct violation of security principles outlined in the OWASP Top Ten. The flaw also maps to ATT&CK technique T1566.002, specifically targeting the exploitation of web application vulnerabilities through forged API requests that bypass authentication mechanisms. The weakness demonstrates how insufficient input validation and improper key management can create persistent security gaps even in seemingly benign plugin functionality.
The recommended mitigation involves updating to MonsterInsights version 11.1.0 or later, which implements proper signature validation regardless of Google Analytics connection status. Administrators should also consider implementing additional monitoring for suspicious AJAX requests and ensure that all WordPress plugins are regularly updated to address known vulnerabilities. Organizations should conduct thorough security assessments of their plugin ecosystem to identify similar cryptographic weaknesses that might exist in other third-party components, as this pattern of empty key handling represents a common vulnerability pattern in web applications that rely on cryptographic signatures for authentication purposes.