CVE-2026-96558
Received Received - Intake

Stored DOM-Based XSS in Quiz and Survey Master WordPress Plugin

Publication date: 2026-10-10

Last updated on: 2026-10-10

Assigner: Wordfence

Description
The Quiz and Survey Master (QSM) – Quiz Maker & Survey Maker plugin for WordPress is vulnerable to Stored DOM-Based Cross-Site Scripting via the 'qsm_hidden_questions' parameter in all versions up to, and including, 11.2.6 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This requires the attacker to force the mlw_results INSERT to fail by submitting an over-length or duplicate qsm_unique_key value, which triggers the audit trail code branch that writes the unescaped payload to wp_mlw_qm_audit_trail.form_data.

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Meta Information

Published
2026-10-10
Last Modified
2026-10-10
Generated
2026-10-10
AI Q&A
2026-10-10
EPSS Evaluated
N/A
NVD
CVE-2026-96558
EUVD
EUVD-2026-96227

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
expresstech Quiz and Survey Master (QSM) – Quiz Maker & Survey Maker 0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

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Executive Summary

This is a Stored DOM-Based Cross-Site Scripting (XSS) vulnerability in the Quiz and Survey Master (QSM) WordPress plugin. It occurs due to insufficient input sanitization and output escaping in the 'qsm_hidden_questions' parameter. Unauthenticated attackers can inject malicious scripts into pages, which execute when users access the infected page. The attack requires triggering a specific code branch by submitting an invalid 'qsm_unique_key' value.

Detection Guidance

Check WordPress installations for the Quiz and Survey Master plugin versions up to and including 11.2.6. Inspect network traffic for suspicious DOM-based XSS payloads in the qsm_hidden_questions parameter. Review audit logs for failed mlw_results INSERT operations or unusual form_data entries in wp_mlw_qm_audit_trail.

Impact Analysis

An attacker could steal user sessions, redirect users to malicious sites, or perform actions on their behalf. Website visitors may have their data compromised, and the site's reputation could be damaged. The vulnerability allows persistent malicious scripts to remain active until removed.

Compliance Impact

This vulnerability could lead to data breaches, violating GDPR's data protection requirements and HIPAA's safeguards for protected health information. Non-compliance may result in legal penalties, fines, and reputational damage for organizations handling sensitive user data.

Mitigation Strategies

Update the Quiz and Survey Master plugin to the latest version beyond 11.2.6. Implement input sanitization for the qsm_hidden_questions parameter. Monitor and restrict access to audit trail logs. Consider disabling the plugin temporarily if an update is not immediately available.

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