CVE-2022-3892 in WP OAuth Server Plugin
Summary
by MITRE • 12/05/2022
The WP OAuth Server (OAuth Authentication) WordPress plugin before 4.2.2 does not sanitize and escape Client IDs, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in multisite setup)
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Analysis
by VulDB Data Team • 12/26/2022
The WP OAuth Server plugin for WordPress represents a critical security vulnerability classified as CVE-2022-3892 that affects versions prior to 4.2.2. This vulnerability stems from inadequate input sanitization and output escaping mechanisms within the plugin's handling of Client IDs, creating a persistent security risk for WordPress installations. The flaw specifically targets the plugin's authentication framework where client identifiers are stored and processed, making it particularly dangerous in multi-tenant environments where administrative privileges may be compromised.
The technical nature of this vulnerability places it squarely within the CWE-79 category of Cross-Site Scripting attacks, specifically manifesting as a stored XSS variant that persists in the database and executes whenever the malicious content is rendered. The vulnerability occurs because the plugin fails to properly sanitize user-supplied Client ID values before storing them in the WordPress database, and subsequently fails to escape these values when outputting them in web pages. This dual failure creates a persistent attack vector where malicious scripts can be injected and executed in the context of authenticated admin sessions, regardless of the standard WordPress security measures that typically restrict unfiltered HTML capabilities.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with elevated privileges within the WordPress environment. High-privilege users such as administrators can be targeted through this stored XSS attack, potentially leading to complete system compromise, data exfiltration, or unauthorized modifications to the WordPress installation. In multisite configurations, where the unfiltered_html capability is typically restricted, this vulnerability becomes even more dangerous as it bypasses these important security restrictions, allowing attackers to execute malicious code that would normally be blocked by WordPress's default security policies.
The attack surface for this vulnerability is particularly concerning in enterprise and multi-user WordPress environments where the OAuth plugin is commonly deployed for third-party authentication integration. Attackers can exploit this weakness by registering malicious client applications with crafted Client IDs containing malicious JavaScript payloads, which then execute whenever administrators view client information or manage authentication settings. The persistence of stored XSS attacks means that the malicious code continues to execute for all users who access the affected plugin interface, making this vulnerability particularly dangerous for long-term compromise of WordPress installations.
Mitigation strategies for this vulnerability require immediate plugin updates to version 4.2.2 or later, which includes proper input sanitization and output escaping mechanisms. Organizations should also implement additional monitoring of OAuth client registrations and conduct thorough security audits of their WordPress installations to identify any potential exploitation attempts. Security teams should consider implementing network-based intrusion detection systems to monitor for suspicious client registration patterns and ensure that all WordPress plugins are regularly updated to address known security vulnerabilities. The ATT&CK framework categorizes this vulnerability under the T1059.007 technique for Scripting, specifically targeting the execution of malicious code through web application vulnerabilities, making it a critical component of comprehensive security posture assessments for WordPress environments.