CVE-2023-0891 in StagTools Plugin
Summary
by MITRE • 05/02/2023
The StagTools WordPress plugin before 2.3.7 does not validate and escape some of its shortcode attributes before outputting them back in a page/post where the shortcode is embed, which could allow users with the contributor role and above to perform Stored Cross-Site Scripting attacks.
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Analysis
by VulDB Data Team • 04/26/2025
The CVE-2023-0891 vulnerability affects the StagTools WordPress plugin version 2.3.6 and earlier, representing a critical stored cross-site scripting flaw that enables authenticated attackers with contributor-level privileges or higher to execute malicious scripts within affected WordPress installations. This vulnerability stems from inadequate input validation and output escaping mechanisms within the plugin's shortcode implementation, creating a persistent security risk that can affect all users who view pages containing compromised shortcodes.
The technical flaw manifests in the plugin's failure to properly sanitize shortcode attributes before rendering them in HTML output contexts. When administrators or contributors insert shortcodes containing malicious payload into posts or pages, the plugin processes these attributes without sufficient validation or escaping, allowing attacker-controlled content to be stored in the database and subsequently executed in the browsers of unsuspecting visitors. This stored XSS vulnerability operates through the standard WordPress shortcode system where user-generated content gets processed and displayed, making it particularly dangerous as the malicious code persists even after the initial injection point.
The operational impact of this vulnerability extends beyond simple script execution, as it enables attackers to perform various malicious activities including session hijacking, credential theft, defacement of content, and redirection to malicious sites. Attackers can leverage this vulnerability to gain unauthorized access to user accounts, modify content, or establish persistence within the WordPress environment. The contributor role escalation capability means that even users with limited privileges can exploit this flaw, making it particularly concerning for sites with multiple contributors or user-generated content systems. The vulnerability affects the core WordPress functionality and can compromise entire sites if exploited successfully.
Mitigation strategies for CVE-2023-0891 should prioritize immediate plugin updates to version 2.3.7 or later, which contain the necessary fixes for input validation and output escaping. Administrators should also implement additional security measures including strict content filtering, regular security audits, and monitoring for suspicious shortcode usage patterns. The vulnerability aligns with CWE-79 which describes Cross-Site Scripting flaws, and represents a specific instance of how insufficient input sanitization leads to persistent XSS attacks. From an ATT&CK framework perspective, this vulnerability maps to T1566.001 (Phishing via Social Media) and T1059.001 (Command and Scripting Interpreter: PowerShell) where attackers could leverage the stored XSS to establish further compromise. Organizations should also consider implementing Content Security Policy (CSP) headers as an additional defense-in-depth measure to limit the potential impact of successful XSS exploitation attempts.