CVE-2026-3617 in Paypal Shortcodes Plugin
Summary
by MITRE • 03/21/2026
The Paypal Shortcode plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'amount' and 'name' shortcode attributes in all versions up to, and including, 0.3. This is due to insufficient input sanitization and output escaping on user-supplied shortcode attributes. The swer_paypal_shortcode() function extracts shortcode attributes using extract() and shortcode_atts() at line 89, then directly concatenates the $name and $amount values into HTML input element value attributes at lines 105-106 without applying esc_attr() or any other escaping function. This makes it possible for authenticated attackers, with Contributor-level access and above, 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 • 03/21/2026
The vulnerability identified as CVE-2026-3617 affects the PayPal Shortcode plugin for WordPress, representing a critical stored cross-site scripting weakness that undermines web application security. This flaw exists within the plugin's handling of user-supplied input through shortcode attributes, specifically targeting the 'amount' and 'name' parameters. The vulnerability stems from inadequate input sanitization and output escaping mechanisms that fail to properly validate or escape user-provided data before its inclusion in HTML output contexts. The issue is particularly concerning because it affects all versions of the plugin up to and including version 0.3, indicating a long-standing security gap that has remained unaddressed.
The technical implementation of this vulnerability occurs within the swer_paypal_shortcode() function where the plugin employs the extract() function combined with shortcode_atts() at line 89 to process incoming shortcode parameters. This approach creates a dangerous precedent where user-supplied values are directly incorporated into HTML markup without proper security measures. The specific flaw manifests when the plugin directly concatenates the $name and $amount variables into HTML input element value attributes at lines 105-106, bypassing essential escaping functions such as esc_attr(). This direct insertion pattern creates an ideal environment for malicious script injection, as the plugin fails to implement proper output encoding or sanitization before rendering user-controllable content within web pages.
The operational impact of this vulnerability extends significantly beyond simple script execution, as it enables authenticated attackers with Contributor-level access or higher to establish persistent malicious code injection points within WordPress installations. This privilege level access requirement does not diminish the severity of the threat, as Contributors typically have substantial capabilities within WordPress environments including the ability to create and edit posts, pages, and media items. The stored nature of this XSS vulnerability means that malicious scripts injected by attackers will persist and execute automatically whenever any user accesses pages containing the compromised shortcode, potentially affecting all visitors to the compromised website. This makes the vulnerability particularly dangerous for sites with high traffic or those that rely on user-generated content, as the attack surface expands with each page containing the vulnerable shortcode.
Security professionals should recognize this vulnerability as a clear example of CWE-79 - Improper Neutralization of Input During Web Page Generation, which specifically addresses the failure to properly escape or sanitize user input before incorporating it into web page contexts. The ATT&CK framework categorizes this as a technique involving code injection within web applications, specifically targeting the web application layer where user input is processed and rendered. Organizations affected by this vulnerability should immediately implement mitigations including plugin updates to versions that properly escape output, implementing strict input validation for shortcode attributes, and deploying web application firewalls that can detect and block malicious script injection attempts. Additionally, administrators should consider implementing role-based access controls to limit Contributor-level permissions where possible, as well as conducting thorough security audits of all installed plugins to identify similar vulnerabilities that may exist within the WordPress ecosystem.
The remediation approach for this vulnerability requires immediate attention through plugin version updates that address the core sanitization and escaping deficiencies. Security teams should prioritize patching affected installations and implement comprehensive input validation mechanisms that prevent malicious data from being processed through the shortcode parsing functions. Organizations should also consider deploying Content Security Policy headers to provide additional defense-in-depth against XSS attacks, though this should not be considered a replacement for proper input sanitization. Regular security assessments of WordPress plugins and themes remain essential to prevent similar vulnerabilities from emerging in other components of the web application stack, particularly focusing on functions that handle user input through shortcode or form processing mechanisms that may be susceptible to similar exploitation patterns.