CVE-2026-2440 in SurveyJS Plugin
Summary
by MITRE • 03/21/2026
The SurveyJS plugin for WordPress is vulnerable to Stored Cross-Site Scripting in all versions up to, and including, 2.5.3 via survey result submissions. This is due to insufficient input sanitization and output escaping. The public survey page exposes the nonce required for submission, allowing unauthenticated attackers to submit HTML-encoded payloads that are decoded and rendered as executable HTML when an administrator views survey results, leading to stored XSS in the admin context.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 03/21/2026
The SurveyJS plugin for WordPress presents a critical stored cross-site scripting vulnerability identified as CVE-2026-2440 affecting versions through 2.5.3. This vulnerability stems from inadequate input sanitization and output escaping mechanisms within the plugin's survey result submission processing. The flaw creates a persistent security risk where malicious payloads can be stored and executed within the administrator's browser context when viewing survey results. The vulnerability specifically manifests through the plugin's handling of survey submissions, where user-provided data is not sufficiently sanitized before being stored in the database. When administrators access the survey results interface, the stored malicious content is rendered without proper HTML escaping, creating an ideal environment for cross-site scripting attacks.
The technical exploitation of this vulnerability occurs through the public survey page which inadvertently exposes the necessary nonce value required for form submissions. This nonce exposure allows unauthenticated attackers to craft and submit malicious payloads that are HTML-encoded during the submission process. However, when these payloads are later retrieved and displayed in the administrator's survey results view, the HTML encoding is insufficiently reversed or escaped, enabling the execution of malicious scripts within the admin context. This stored XSS vulnerability operates under CWE-79 which classifies improper neutralization of input during web output, specifically targeting the failure to properly escape output in web applications. The vulnerability represents a classic case of insufficient output escaping where the plugin fails to properly sanitize user input before rendering it in administrative contexts.
The operational impact of this vulnerability extends beyond simple script execution as it provides attackers with persistent access to administrative functions within the WordPress environment. When administrators view survey results containing malicious payloads, the stored XSS can be leveraged to execute arbitrary JavaScript code in their browser sessions, potentially leading to complete administrative compromise. Attackers can exploit this vulnerability to steal session cookies, modify survey configurations, or even inject additional malicious content into the WordPress installation. The attack vector is particularly concerning because it requires no authentication from the attacker to submit the malicious payload, making it an attractive target for automated exploitation. This vulnerability directly aligns with ATT&CK technique T1566 which covers phishing with malicious attachments and links, as the malicious payloads can be embedded within survey submissions that appear legitimate to end users.
Mitigation strategies for CVE-2026-2440 should prioritize immediate plugin updates to versions that address the input sanitization and output escaping deficiencies. Administrators should implement comprehensive input validation and output escaping mechanisms that properly encode all user-provided content before storage and rendering. The plugin should be configured to avoid exposing nonce values on public pages and should implement proper access controls for survey result viewing. Security measures should include regular monitoring for suspicious survey submissions and implementing Content Security Policy headers to limit script execution capabilities. Additionally, administrators should consider implementing Web Application Firewall rules that can detect and block suspicious payload patterns, while maintaining detailed audit logs of survey result access and modification activities. The vulnerability demonstrates the critical importance of proper input validation and output escaping in preventing stored cross-site scripting attacks, particularly in plugins that handle user-submitted data in administrative contexts.