CVE-2022-1095 in No External Links Plugin
Summary
by MITRE • 06/27/2022
The Mihdan: No External Links WordPress plugin through 4.8.0 does not sanitise and escape some of its settings, 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 • 07/15/2022
The vulnerability identified as CVE-2022-1095 affects the Mihdan: No External Links WordPress plugin version 4.8.0 and earlier, representing a critical security flaw that undermines the platform's content sanitization mechanisms. This issue specifically targets the plugin's handling of user settings where input validation and output escaping are insufficiently implemented. The vulnerability stems from the plugin's failure to properly sanitize user-supplied data before storing it in the WordPress database and subsequently rendering it in web pages without adequate HTML escaping. This oversight creates a persistent security risk where malicious scripts can be injected into plugin settings and executed whenever the affected pages are loaded.
The technical nature of this vulnerability places it firmly within the category of stored cross-site scripting attacks as defined by CWE-079, which occurs when user-controllable data is stored and then later rendered in a web page without proper sanitization. The flaw is particularly concerning because it affects high-privilege users including administrators who typically possess elevated capabilities within WordPress systems. Even when WordPress multisite installations restrict the unfiltered_html capability to prevent unrestricted HTML injection, this vulnerability allows attackers to bypass such protections through the plugin's settings interface. The security implications extend beyond simple XSS execution as it enables attackers to manipulate the plugin's functionality and potentially escalate their privileges within the WordPress environment.
The operational impact of this vulnerability is significant for WordPress installations utilizing the affected plugin, particularly in multi-user environments where administrative privileges are distributed across multiple users. Attackers with admin-level access can craft malicious scripts within the plugin's settings that will execute in the context of other users' browsers when they view pages containing the plugin's functionality. This creates a persistent threat vector that can be exploited to steal session cookies, perform unauthorized actions on behalf of users, or redirect victims to malicious websites. The vulnerability's persistence is enhanced by the fact that stored XSS attacks remain active until the malicious content is explicitly removed from the database, making it particularly dangerous for long-term deployments. The exploitation of this vulnerability aligns with ATT&CK technique T1566.001 for initial access through malicious links and T1059.001 for command and control through script execution, making it a critical concern for security operations teams managing WordPress environments.
Mitigation strategies for CVE-2022-1095 should prioritize immediate plugin updates to versions that address the sanitization issues, as the vendor has likely released patches to resolve the stored XSS vulnerability. Organizations should implement comprehensive input validation and output escaping measures for all user-controllable settings within WordPress plugins, ensuring that any data stored in the database is properly sanitized before being rendered in web contexts. Security teams should conduct thorough audits of all installed plugins to identify similar sanitization weaknesses and consider implementing automated scanning tools to detect potential XSS vulnerabilities in custom or third-party WordPress components. Additionally, administrators should review and restrict plugin capabilities where possible, ensuring that only necessary permissions are granted to high-privilege users while maintaining the principle of least privilege across the WordPress installation. The vulnerability underscores the critical importance of proper input validation and output escaping practices in web applications, particularly those handling user-generated content or configuration data.