CVE-2022-4562 in Meks Flexible Shortcodes Plugin
Summary
by MITRE • 02/13/2023
The Meks Flexible Shortcodes WordPress plugin before 1.3.5 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 • 03/12/2023
The vulnerability identified as CVE-2022-4562 affects the Meks Flexible Shortcodes WordPress plugin version 1.3.4 and earlier, representing a critical security flaw that undermines the integrity of WordPress installations. This issue stems from inadequate input validation and output escaping mechanisms within the plugin's shortcode processing functionality, creating a pathway for malicious actors to inject persistent malicious code into web pages. The vulnerability is particularly concerning because it can be exploited by users with minimal privileges, specifically contributors who typically have limited capabilities within WordPress systems. The flaw enables attackers to execute stored cross-site scripting attacks that can target high-privilege users including administrators, making this vulnerability particularly dangerous in multi-user environments where role-based access controls are expected to maintain security boundaries.
The technical implementation of this vulnerability resides in the plugin's failure to properly sanitize shortcode attributes before rendering them in HTML output contexts. When users with contributor roles create or modify content using the plugin's shortcodes, the system does not adequately validate or escape potentially malicious input values that are then stored in the database and subsequently displayed in subsequent page renders. This stored XSS vulnerability allows attackers to inject malicious JavaScript code through shortcode parameters, which executes whenever the affected page is loaded by any user, including administrators. The vulnerability is classified under CWE-79 as a Cross-Site Scripting flaw, specifically a stored variant where malicious input is permanently stored and then executed in the victim's browser. The ATT&CK framework categorizes this as a technique for code injection and privilege escalation, as it allows low-privilege users to potentially gain access to administrative functions through session hijacking or credential theft.
The operational impact of CVE-2022-4562 extends beyond simple script execution, as it creates persistent backdoors within WordPress installations that can be leveraged for ongoing attacks. High-privilege administrators who view pages containing the malicious shortcodes become unwitting participants in the attack chain, as their browser sessions can be hijacked or their credentials can be harvested through the executed malicious scripts. This vulnerability enables attackers to perform actions such as modifying content, stealing cookies, redirecting users to malicious sites, or even installing additional malware. The stored nature of the vulnerability means that even after the initial injection, the malicious code continues to execute automatically whenever the affected pages are accessed, providing attackers with persistent access to the compromised system. The attack surface is further expanded as administrators may unknowingly create or modify content using the vulnerable plugin, inadvertently maintaining the malicious payload within the system.
Mitigation strategies for CVE-2022-4562 require immediate action to upgrade the Meks Flexible Shortcodes plugin to version 1.3.5 or later, which contains the necessary patches to address the input validation and output escaping deficiencies. Organizations should also implement comprehensive monitoring of their WordPress installations to detect any suspicious shortcode usage or unauthorized content modifications that may indicate exploitation attempts. Security teams should conduct thorough audits of all active plugins to identify similar vulnerabilities and ensure proper input validation mechanisms are in place across the entire WordPress ecosystem. Additional protective measures include implementing content security policies that restrict script execution and limiting the capabilities of contributor-level users where possible. The vulnerability demonstrates the critical importance of proper input validation and output escaping practices, particularly in web applications that process user-generated content, as highlighted by security best practices outlined in OWASP Top Ten and similar industry standards. Regular security assessments and vulnerability scanning should be implemented to proactively identify and remediate similar issues before they can be exploited by threat actors.