CVE-2022-4459 in WP Show Posts Plugin
Summary
by MITRE • 02/06/2023
The WP Show Posts WordPress plugin before 1.1.4 does not validate and escape some of its shortcode attributes before outputting them back in the page, which could allow users with a role as low as contributor to perform Stored Cross-Site Scripting attacks which could be used against high privilege users such as admins.
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Analysis
by VulDB Data Team • 03/05/2023
The WP Show Posts WordPress plugin vulnerability CVE-2022-4459 represents a critical stored cross-site scripting flaw that affects versions prior to 1.1.4. This vulnerability exists within the plugin's handling of shortcode attributes, where insufficient input validation and output escaping mechanisms fail to properly sanitize user-supplied data before rendering it back to web pages. The flaw specifically targets the plugin's shortcode processing functionality, which allows users to dynamically generate content displays on WordPress sites. Attackers exploiting this vulnerability can inject malicious scripts through carefully crafted shortcode parameters that are then stored and executed when the content is rendered to other users.
The technical nature of this vulnerability places it squarely within the CWE-79 category of Cross-Site Scripting, specifically classified as a stored XSS variant where malicious payloads are persisted in the application's database or storage mechanisms. The vulnerability's severity is amplified by the low privilege level required to exploit it, as users with contributor roles can leverage this flaw to compromise higher-privilege accounts such as administrators. This makes the attack vector particularly dangerous in multi-user WordPress environments where contributor-level access might be granted to less trusted users or automated systems. The vulnerability demonstrates a classic failure in the principle of least privilege and proper input sanitization within web application security frameworks.
From an operational impact perspective, this vulnerability creates significant risk for WordPress site administrators who may not be aware that their contributors could potentially execute malicious scripts against other users. The stored nature of the XSS means that once a malicious shortcode is submitted and processed, the payload remains active until explicitly removed or the plugin is updated. High privilege users such as administrators who view pages containing the malicious content become vulnerable to session hijacking, credential theft, or other malicious activities that could compromise entire site operations. The vulnerability also represents a potential pathway for attackers to escalate privileges, gain persistent access to the WordPress installation, or use the compromised site as a launching point for broader attacks against the hosting environment.
The recommended mitigation strategy involves immediate deployment of the patched version 1.1.4 or later, which addresses the core sanitization issues in the plugin's shortcode attribute handling. Administrators should also implement additional security measures including role-based access controls to limit contributor capabilities, regular security audits of installed plugins, and monitoring for suspicious shortcode usage patterns. Organizations should consider implementing content security policies to limit the execution of malicious scripts, though this provides only secondary protection. The vulnerability highlights the importance of proper input validation and output escaping practices as outlined in OWASP Top Ten security guidelines, and represents a clear example of why all user-supplied content must be properly sanitized before being processed or displayed within web applications. Security teams should also conduct thorough vulnerability assessments of all installed WordPress plugins to identify similar issues that might exist in other components of their web application infrastructure.