CVE-2021-25086 in Advanced Page Visit Counter Plugin
Summary
by MITRE • 05/02/2022
The Advanced Page Visit Counter WordPress plugin through 5.0.8 does not sanitise and escape some input before outputting it in an admin dashboard page, allowing unauthenticated attackers to perform Cross-Site Scripting attacks against admins viewing it
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Analysis
by VulDB Data Team • 05/05/2022
The CVE-2021-25086 vulnerability resides within the Advanced Page Visit Counter WordPress plugin version 5.0.8 and earlier, representing a critical cross-site scripting flaw that undermines the security of WordPress administrative interfaces. This vulnerability specifically affects the plugin's handling of user input within admin dashboard pages, creating an avenue for unauthenticated attackers to inject malicious scripts into the administrative environment. The flaw manifests when the plugin fails to properly sanitize and escape data before rendering it in the admin interface, thereby exposing administrators to potential script execution attacks. The vulnerability's severity is amplified by the fact that it requires no authentication to exploit, making it particularly dangerous as attackers can target administrators without needing valid credentials or access rights.
The technical implementation of this vulnerability stems from improper input validation and output escaping mechanisms within the plugin's codebase. When administrators view pages containing data processed by the Advanced Page Visit Counter plugin, any unsanitized input that gets rendered in the admin dashboard becomes executable code. This represents a classic XSS vulnerability pattern where data flows from an untrusted source through the application to a trusted sink without proper sanitization. The flaw directly relates to CWE-79 which defines cross-site scripting as the failure to properly escape output, and aligns with ATT&CK technique T1566.001 which describes social engineering via malicious content injection. Attackers can craft malicious payloads that, when viewed by administrators, execute in their browser context and potentially lead to session hijacking, privilege escalation, or further system compromise.
The operational impact of CVE-2021-25086 extends beyond simple script execution as it creates a persistent threat vector within WordPress environments. Administrators who regularly access the dashboard are at risk of having their sessions compromised through stored XSS attacks, where malicious scripts are stored on the server and executed whenever administrators view affected pages. This vulnerability can enable attackers to steal administrator cookies, perform unauthorized actions within the WordPress admin panel, or even exfiltrate sensitive data from the administration interface. The unauthenticated nature of the attack means that any user with access to the WordPress site can potentially exploit this flaw, making it particularly dangerous in public-facing environments where the plugin is installed. The vulnerability also poses risks to the broader WordPress ecosystem as successful exploitation could lead to complete administrative control over the site.
Mitigation strategies for CVE-2021-25086 must address both immediate remediation and long-term prevention measures. The most direct solution involves updating the Advanced Page Visit Counter plugin to version 5.0.9 or later, where the sanitization and escaping issues have been resolved. Organizations should implement comprehensive patch management procedures to ensure all WordPress plugins remain current with security updates. Additionally, administrators should consider implementing content security policies to limit script execution within the admin dashboard, though this serves as a secondary defense rather than a primary fix. Network-level monitoring should be enhanced to detect suspicious script injection attempts, and regular security audits should verify that no other plugins suffer from similar sanitization issues. The vulnerability also underscores the importance of input validation practices and proper output escaping as fundamental security controls, aligning with security frameworks that emphasize defense in depth and the principle of least privilege in web application development.