CVE-2023-1929 in WP Fastest Cache Plugin
Summary
by MITRE • 04/07/2023
The WP Fastest Cache plugin for WordPress is vulnerable to unauthorized data modification due to a missing capability check on the wpfc_purgecache_varnish_callback function in versions up to, and including, 1.1.2. This makes it possible for authenticated attackers with subscriber-level access to purge the varnish cache.
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Analysis
by VulDB Data Team • 04/09/2026
The WP Fastest Cache plugin represents a widely used caching solution for wordpress environments that significantly improves website performance by storing static versions of pages. This particular vulnerability exists within the plugin's handling of cache purging operations, specifically targeting the wpfc_purgecache_varnish_callback function. The flaw manifests as a critical access control weakness that allows authenticated users to perform actions they should not be authorized to execute, creating a privilege escalation vector within the wordpress administration framework.
The technical implementation of this vulnerability stems from the absence of proper capability verification within the targeted callback function. When an authenticated user with subscriber privileges attempts to trigger cache purging operations, the system fails to validate whether the user possesses the necessary administrative permissions required to execute such operations. This missing capability check creates a direct pathway for unauthorized modification of the cache system, effectively allowing low-privilege users to manipulate high-value system resources. The vulnerability specifically affects versions up to and including 1.1.2, indicating that the issue was present in the plugin's core architecture before remediation efforts were implemented.
The operational impact of this vulnerability extends beyond simple cache manipulation, as it represents a fundamental breakdown in the wordpress security model's privilege separation mechanisms. An attacker with subscriber-level access can leverage this flaw to disrupt service availability, potentially causing website performance degradation or complete unavailability. The ability to purge varnish cache specifically targets the edge caching infrastructure that many wordpress sites rely upon for content delivery optimization, making this vulnerability particularly dangerous for high-traffic websites. This weakness enables attackers to systematically undermine the performance benefits that caching systems are designed to provide.
From a cybersecurity perspective, this vulnerability aligns with common weakness enumerations such as CWE-284, which addresses improper access control in software systems. The flaw demonstrates how seemingly minor implementation oversights can create significant security risks within content management systems. The attack pattern follows typical privilege escalation techniques described in the attack technique framework, where authenticated users exploit missing authorization checks to gain elevated capabilities. Organizations using this plugin should immediately implement mitigation strategies including plugin updates, capability restriction policies, and monitoring for unauthorized cache manipulation attempts to prevent exploitation of this vulnerability.
The remediation approach requires immediate patching of the affected plugin versions, with administrators verifying that all instances have been updated to the latest secure release. Additional defensive measures should include implementing role-based access controls that limit cache management capabilities to authorized administrators only, establishing monitoring protocols for cache purging activities, and conducting regular security assessments of third-party wordpress plugins. The vulnerability serves as a critical reminder of the importance of proper access control implementation in web applications and the necessity of thorough security testing for all authentication-related functions within content management systems.