CVE-2026-27397 in Really Simple Security Pro Plugin
Summary
by MITRE • 03/19/2026
Authorization Bypass Through User-Controlled Key vulnerability in Really Simple Plugins B.V. Really Simple Security Pro allows Exploiting Incorrectly Configured Access Control Security Levels.This issue affects Really Simple Security Pro: from n/a through 9.5.4.0.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 03/22/2026
The CVE-2026-27397 vulnerability represents a critical authorization bypass flaw within the Really Simple Security Pro plugin developed by Really Simple Plugins B.V. This vulnerability specifically targets the plugin's access control mechanisms and allows attackers to exploit incorrectly configured security levels through user-controlled keys. The issue exists across all versions of the plugin from the initial release through version 9.5.4.0, indicating a long-standing security weakness that has not been adequately addressed. The vulnerability falls under the broader category of improper access control flaws that can severely compromise the security posture of WordPress installations relying on this plugin. The affected plugin is designed to enhance security for WordPress sites, yet contains a fundamental flaw that undermines its protective capabilities.
The technical implementation of this vulnerability stems from how the plugin handles user-controlled keys within its authorization framework. Attackers can manipulate these keys to bypass intended access controls and gain unauthorized access to restricted functionality within the plugin's administrative interfaces. This flaw typically occurs when the application fails to properly validate or sanitize user inputs that are used as keys for access control decisions. The vulnerability enables an attacker to escalate privileges or access sensitive administrative features without proper authentication, effectively rendering the plugin's security measures ineffective. The issue demonstrates poor input validation practices and inadequate access control enforcement mechanisms that allow attackers to manipulate the system's security decisions through crafted user inputs.
The operational impact of this vulnerability is severe and multifaceted for affected WordPress installations. An attacker who successfully exploits this authorization bypass can gain administrative access to the WordPress site, potentially leading to complete compromise of the installation. This includes the ability to modify content, install malicious plugins, change user permissions, and access sensitive data stored within the site. The vulnerability also poses risks to the broader network if the compromised WordPress site serves as a foothold for further attacks. Organizations relying on Really Simple Security Pro for their security infrastructure may experience unauthorized access to their administrative interfaces, potentially resulting in data breaches, site defacement, or the installation of backdoors. The impact extends beyond individual site compromise to potential cascading effects within larger network environments.
Mitigation strategies for CVE-2026-27397 should prioritize immediate action to address the vulnerability. Organizations should upgrade to the latest available version of Really Simple Security Pro where the issue has been patched, or implement temporary workarounds such as disabling the vulnerable plugin functionality until a proper update is applied. Network administrators should monitor for suspicious access patterns and implement additional security controls including multi-factor authentication and enhanced monitoring of administrative interfaces. The vulnerability aligns with CWE-285 which addresses improper authorization issues, and can be categorized under ATT&CK technique T1078 for valid accounts and T1566 for credential harvesting. Security teams should also conduct comprehensive audits of their WordPress installations to identify other potential access control vulnerabilities and ensure proper input validation across all security components. Regular security assessments and vulnerability scanning should be implemented to detect similar flaws in other plugins and themes that may present similar authorization bypass risks.