CVE-2026-13342 in Security Optimizer Plugin
Summary
by MITRE • 08/07/2026
The Security Optimizer WordPress plugin from 1.5.8 to 1.6.4 does not correctly validate requests to its optional IP-based login restriction feature, allowing the restriction to be bypassed so that unauthenticated requests from non-allowlisted IP addresses can reach and use the login form, defeating the access control the administrator configured.
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Analysis
by VulDB Data Team • 08/07/2026
The Security Optimizer WordPress plugin presents a critical access control vulnerability that undermines the intended security posture of its IP-based login restriction feature. This flaw exists within plugin versions ranging from 1.5.8 through 1.6.4 and represents a direct violation of secure coding practices for authentication mechanisms. The vulnerability stems from improper request validation within the plugin's optional IP restriction functionality, creating a pathway for unauthorized access that completely defeats the administrator's configured access controls.
The technical implementation flaw manifests in the plugin's failure to properly validate incoming requests before granting access to the login form. When administrators configure IP-based restrictions, they expect only allowlisted IP addresses to be able to reach the authentication interface. However, due to insufficient validation logic, the plugin accepts and processes requests from any IP address regardless of whether they fall within the configured allowlist. This represents a classic authorization bypass vulnerability that can be classified under CWE-285, which deals with improper authorization in access control mechanisms.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass potential account takeover scenarios and brute force attacks. Attackers can exploit this weakness to systematically attempt login credentials from non-allowlisted IP addresses, effectively neutralizing the intended security boundary. The vulnerability allows adversaries to bypass the first line of defense that administrators typically implement to restrict login access to trusted networks or locations. This creates an environment where automated attack tools can leverage the bypassed restriction to conduct credential stuffing, password spraying, or brute force attacks against the WordPress installation.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1110 which covers credential access through brute force and password spraying attacks. The flaw essentially removes the network-level control that administrators rely on for access restriction, creating an attack surface that would otherwise be mitigated by IP-based restrictions. Security professionals should note that this vulnerability affects the fundamental security controls that organizations implement to reduce authentication attack surfaces, particularly in environments where administrators expect network-level filtering to protect sensitive login interfaces.
Mitigation strategies should include immediate plugin updates to versions that address this validation flaw, as well as implementing additional layers of protection such as two-factor authentication and rate limiting mechanisms. Organizations should also conduct thorough audits of their WordPress installations to identify other plugins with similar access control vulnerabilities. The recommended remediation approach involves ensuring proper input validation and request verification before granting access to authentication interfaces, which aligns with security best practices established in OWASP Top Ten and NIST cybersecurity frameworks. Additionally, administrators should consider implementing web application firewalls or intrusion prevention systems that can detect and block suspicious login attempts even when the underlying plugin vulnerability exists.