CVE-2025-1689 in PayPal Express Checkout Plugin
Summary
by MITRE • 02/27/2025
The ThemeMakers PayPal Express Checkout plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'paypal' shortcode in versions up to, and including, 1.1.9 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers with contributor-level and above permissions to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
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Analysis
by VulDB Data Team • 02/27/2025
The vulnerability identified as CVE-2025-1689 affects the ThemeMakers PayPal Express Checkout plugin for WordPress, specifically targeting versions up to and including 1.1.9. This represents a critical security flaw that enables stored cross-site scripting attacks through the plugin's 'paypal' shortcode implementation. The vulnerability stems from inadequate input sanitization and output escaping mechanisms that fail to properly validate or sanitize user-supplied attributes before processing them within the plugin's shortcode functionality.
The technical flaw manifests when authenticated attackers with contributor-level permissions or higher exploit the insufficient validation controls to inject malicious JavaScript code through the paypal shortcode parameters. These injected scripts become permanently stored within the WordPress database and execute whenever any user accesses pages containing the compromised shortcode, creating a persistent threat vector that can affect all users who encounter the malicious content. This vulnerability operates under the CWE-79 classification for cross-site scripting flaws, specifically targeting stored XSS conditions where malicious payloads are saved and executed later rather than reflected in real-time responses.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with the ability to perform various malicious activities including session hijacking, credential theft, and data exfiltration. Contributors and higher-level users possess sufficient privileges to modify content and insert the malicious shortcode into pages, making this attack surface particularly concerning for WordPress installations where multiple users have content management capabilities. The stored nature of the vulnerability means that once exploited, the malicious code remains persistent until manually removed from the database, potentially affecting all users who access affected pages.
Mitigation strategies should focus on immediate plugin updates to versions that address the sanitization and escaping deficiencies, while also implementing additional security measures such as input validation at multiple layers and enhanced output encoding for all user-supplied data. Organizations should consider restricting contributor-level permissions to minimize the attack surface and implement web application firewalls that can detect and block suspicious shortcode parameter patterns. The vulnerability aligns with ATT&CK technique T1566.001 for credential access through social engineering and T1059.001 for command and scripting interpreter execution, emphasizing the need for comprehensive defensive measures. Regular security audits of WordPress plugins and proactive monitoring of user content modifications remain essential practices for preventing exploitation of similar vulnerabilities in the WordPress ecosystem.