CVE-2021-24481 in Any Hostname Plugin
Summary
by MITRE • 08/02/2021
The Any Hostname WordPress plugin through 1.0.6 does not sanitise or escape its "Allowed hosts" setting, leading to an authenticated stored XSS issue as high privilege users are able to set XSS payloads in it
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Analysis
by VulDB Data Team • 08/06/2021
The CVE-2021-24481 vulnerability affects the Any Hostname WordPress plugin version 1.0.6 and earlier, representing a critical security flaw that enables authenticated stored cross-site scripting attacks. This vulnerability arises from the plugin's failure to properly sanitise or escape user input within its "Allowed hosts" configuration setting, creating a persistent XSS vector that can be exploited by high-privilege users who have access to the plugin's settings interface.
The technical flaw stems from improper input validation and output escaping mechanisms within the plugin's administrative interface. When authorised users with sufficient privileges modify the "Allowed hosts" setting, the plugin fails to implement adequate sanitisation measures to prevent malicious script code from being stored in the WordPress database. This stored malicious content becomes executable whenever the affected page is rendered, allowing attackers to inject arbitrary JavaScript code that executes in the context of other users' browsers. The vulnerability specifically targets authenticated users with administrative capabilities, making it particularly dangerous as it leverages legitimate access privileges to bypass security controls.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with the ability to perform various malicious activities including session hijacking, data theft, privilege escalation, and redirection to malicious websites. Since the vulnerability affects high-privilege users, attackers could potentially gain complete control over WordPress installations, manipulate content, steal sensitive information, or establish persistent backdoors. The stored nature of the XSS payload means that the attack remains effective until the malicious code is manually removed from the plugin settings, making it particularly insidious and difficult to detect. This vulnerability aligns with CWE-79 which describes cross-site scripting flaws, and represents a clear violation of secure coding practices that should prevent untrusted data from being directly embedded into web pages without proper sanitisation.
Mitigation strategies for CVE-2021-24481 should include immediate patching of the Any Hostname plugin to version 1.0.7 or later, which contains the necessary sanitisation fixes. Administrators should also implement additional security measures such as monitoring plugin settings changes, restricting administrative access to trusted users only, and implementing web application firewalls that can detect and block malicious script payloads. The vulnerability demonstrates the importance of input validation and output escaping as fundamental security practices, reinforcing the need for proper sanitisation of all user-provided data before storage or rendering. Security teams should conduct thorough audits of all installed plugins to identify similar vulnerabilities and ensure that all administrative interfaces properly implement security controls to prevent stored XSS attacks. This incident highlights the critical importance of maintaining up-to-date software and following security best practices to prevent exploitation of authenticated vulnerabilities that can lead to complete system compromise.