ChatterMate hat Stored Cross-Site Scripting (XSS) via Chatbot Input Execution

The impact of this XSS vulnerability is significant. An attacker can inject arbitrary JavaScript code into the ChatterMate chatbot interface. This code can then be executed in the context of the user's browser, granting the attacker access to sensitive client-side data. Specifically, the vulnerability allows access to localStorage tokens and cookies, which could be used to hijack user sessions, impersonate users, or perform unauthorized actions. The use of an <iframe> payload containing a javascript: URI makes exploitation relatively straightforward. This vulnerability resembles other XSS attacks where malicious scripts are injected to compromise user accounts and data.

Organizations deploying ChatterMate for customer service, internal communication, or any application where user input is processed by the chatbot are at risk. Specifically, deployments using default configurations without input validation are particularly vulnerable. Any environment where sensitive user data is stored in browser local storage is also at increased risk.

• javascript / web:

// Check for suspicious iframes in chatbot input logs
// Look for javascript: URIs within iframe src attributes

• generic web:

# Check access logs for requests containing javascript: URIs
grep 'javascript:' /var/log/apache2/access.log

1. 2026-01-24Disclosure

   disclosure

1. Reserviert2026-01-22
2. Veröffentlicht2026-01-24
3. Geändert2026-01-26
4. EPSS aktualisiert2026-03-23

The primary mitigation for CVE-2026-24399 is to immediately upgrade ChatterMate to version 1.0.9 or later. If upgrading is not immediately feasible, consider implementing input validation and sanitization on the chatbot's input fields to prevent the injection of malicious HTML/JavaScript. Web Application Firewalls (WAFs) configured to detect and block XSS payloads can provide an additional layer of defense. Regularly review and update chatbot configurations to minimize the attack surface. After upgrading, confirm the fix by attempting to inject a known malicious payload (e.g., <img src=x onerror=alert(1)>) and verifying that it is not executed.