CVE-2026-104000
Received Received - Intake

Stored XSS in Simply Schedule Appointments WordPress Plugin

Publication date: 2026-10-16

Last updated on: 2026-10-16

Assigner: Wordfence

Description
The Simply Schedule Appointments plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'status' parameter in all versions up to, and including, 1.6.12.35 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. The malicious payload is stored unconditionally because debug logging is enabled by default, and the debug-log viewer is accessible to anyone holding the site-wide Support PIN (an HMAC-MD5 of AUTH_SALT displayed in wp-admin), meaning the injected script will execute against the administrator's session during ordinary support or troubleshooting workflows.

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Meta Information

Published
2026-10-16
Last Modified
2026-10-16
Generated
2026-10-16
AI Q&A
2026-10-16
EPSS Evaluated
N/A
NVD
CVE-2026-104000
EUVD
EUVD-2026-102663

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
croixhaug Simply Schedule Appointments 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 vulnerability is a Stored Cross-Site Scripting (XSS) flaw in the Simply Schedule Appointments WordPress plugin. It allows unauthenticated attackers to inject malicious scripts via the 'status' parameter due to poor input sanitization and output escaping. The scripts are stored unconditionally because debug logging is enabled by default and the debug-log viewer is accessible to anyone with the site-wide Support PIN.

Detection Guidance

Check for the Simply Schedule Appointments plugin version up to 1.6.12.35. Inspect web server logs for unusual script injections in the 'status' parameter. Look for the Support PIN exposure in wp-admin settings.

Impact Analysis

An attacker could inject malicious scripts that execute when an administrator accesses an infected page. This could lead to session hijacking, unauthorized actions on the site, or theft of sensitive data like login credentials. The attack is persistent as the payload remains stored in the plugin's debug logs.

Compliance Impact

This vulnerability could lead to unauthorized access or data breaches, violating GDPR's data protection requirements or HIPAA's safeguards for protected health information. Organizations may face legal penalties, reputational damage, and loss of customer trust if exploited.

Mitigation Strategies

Update the Simply Schedule Appointments plugin to the latest version. Disable debug logging if enabled. Restrict access to the Support PIN and wp-admin area. Monitor for unauthorized script injections in web pages.

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