CVE-2026-4604 in Membership Request Plugin
Summary
by MITRE • 07/29/2026
The Klubraum Membership Request plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the `kr_mr_store_settings()` function in all versions up to, and including, 1.1.0. This makes it possible for unauthenticated attackers to update the plugin's settings, including the Klubraum API token and introduction text, effectively hijacking the plugin's integration with the Klubraum service.
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Analysis
by VulDB Data Team • 07/29/2026
The Klubraum Membership Request plugin for WordPress presents a critical security vulnerability that stems from inadequate access control mechanisms within its core functionality. This vulnerability exists in all versions up to and including 1.1.0, where the `kr_mr_store_settings()` function fails to perform proper capability checks before allowing modifications to plugin settings. The absence of authentication verification creates an exploitable pathway for malicious actors to manipulate sensitive configuration parameters without possessing legitimate administrative credentials.
This security flaw fundamentally compromises the integrity of the plugin's operational environment by enabling unauthorized data modification through a missing capability check vulnerability classified under CWE-284. The vulnerability allows unauthenticated attackers to gain access to critical system configurations that control the plugin's integration with external services, specifically targeting the Klubraum API token and introduction text parameters. The implications extend beyond simple configuration changes as these settings directly influence how the plugin communicates with the Klubraum service, potentially enabling complete hijacking of the integration.
The operational impact of this vulnerability creates significant risk for WordPress sites utilizing the Klubraum Membership Request plugin, as attackers can effectively take control of the service integration without requiring any authentication credentials. This unauthorized modification capability enables threat actors to alter the API token, which serves as the primary authentication mechanism between the WordPress installation and the Klubraum service, potentially allowing them to redirect traffic or gain access to sensitive membership data. Additionally, modifications to the introduction text could be used for social engineering attacks or to inject malicious content into the site's user-facing interfaces.
From an attacker perspective, this vulnerability aligns with ATT&CK technique T1078.004 which involves valid accounts being used to perform privileged actions, but in this case the attack occurs through a lack of proper access controls rather than compromised credentials. The missing capability check represents a fundamental flaw in the plugin's privilege management system that violates basic security principles of least privilege and proper authorization enforcement. Organizations should immediately implement mitigations including upgrading to patched versions, implementing network-level restrictions, or disabling the affected plugin until proper updates are applied to prevent exploitation attempts that could lead to full service compromise.
The vulnerability demonstrates how simple oversight in capability validation can create substantial security risks within content management systems, particularly when dealing with external service integrations where API tokens and configuration parameters represent critical attack vectors. Proper implementation of capability checks would have prevented unauthorized access to sensitive settings while maintaining legitimate administrative functionality, highlighting the importance of following established security frameworks such as those defined in the OWASP Top Ten and NIST cybersecurity guidelines for web application development.