CVE-2026-107763 in Fastcache by Host.it Plugin
Summary
by MITRE • 10/17/2026
The Fastcache by Host.it plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 1.7.5. This is due to the plugin not properly verifying that a user is authorized to perform an action. This makes it possible for authenticated attackers, with subscriber-level access and above, to add or remove the plugin's page-cache rewrite rules in the site's root .htaccess file.
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Analysis
by VulDB Data Team • 10/17/2026
The vulnerability identified within the Fastcache by Host.it WordPress plugin affects all versions up to and including 1.7.5, representing a critical flaw in access control mechanisms that undermines the integrity of server configuration files. This issue stems from an authorization bypass where the application fails to adequately verify whether the initiating user possesses the necessary privileges to execute specific administrative actions. In secure software design, operations that modify core infrastructure settings must be strictly gated behind high-level permissions; however, this plugin allows authenticated users with subscriber-level access and above to interact with sensitive configuration endpoints without sufficient validation of their role or intent.
From a technical perspective, the flaw enables attackers who have obtained valid credentials for even low-privileged accounts, such as subscribers, to manipulate the site's root .htaccess file. This file is pivotal in Apache-based web server configurations, dictating how requests are handled, including URL rewriting and caching rules. By adding or removing page-cache rewrite rules through this vulnerability, an attacker can alter the fundamental behavior of the website’s request processing pipeline. This capability allows for significant disruption to service availability by breaking cache mechanisms that ensure performance stability, potentially leading to increased server load and degraded user experience during traffic spikes.
The operational impact extends beyond mere configuration changes, as manipulating rewrite rules can facilitate more severe attacks such as cross-site scripting or information disclosure if the altered rules inadvertently expose sensitive directories or files. Furthermore, this vulnerability aligns with CWE-269, which describes Improper Privilege Control, indicating that the software does not enforce appropriate separation of duties between user roles. The ability to modify server configuration via a web application interface also maps to ATT&CK technique T1505.003, Server Software Component: Web Shell, or more broadly T1222.002, File and Directory Permissions Modification, depending on the specific outcome of the rule changes. Attackers can leverage this access to establish persistence mechanisms or disrupt business continuity by rendering the site inaccessible through misconfigured caching rules that cause infinite loops or 500 internal server errors.
Mitigation strategies must prioritize immediate remediation due to the high severity of modifying core infrastructure files from a low-privileged account. The most effective solution is to upgrade the Fastcache plugin to a version later than 1.7.5, where developers have presumably implemented proper role-based access control checks for administrative functions. In environments where upgrading is not immediately feasible, administrators should restrict user roles that require such privileges strictly to trusted individuals with administrator-level access. Additionally, implementing web application firewalls can help detect and block anomalous requests targeting .htaccess modification endpoints, while regular auditing of file integrity on the server side provides an additional layer of defense against unauthorized configuration changes.