CVE-2026-24399 Overview
CVE-2026-24399 is a critical Cross-Site Scripting (XSS) vulnerability affecting ChatterMate, a no-code AI chatbot agent framework. In versions 1.0.8 and below, the chatbot fails to properly sanitize user-supplied chat input, allowing attackers to inject and execute malicious HTML and JavaScript payloads within the browser context. This client-side injection vulnerability can be exploited to steal sensitive data including localStorage tokens and session cookies.
Critical Impact
Attackers can execute arbitrary JavaScript in victim browsers through malicious chat input, potentially leading to session hijacking, credential theft, and unauthorized access to sensitive client-side data.
Affected Products
- ChatterMate versions 1.0.8 and below
- ChatterMate AI chatbot framework deployments using vulnerable versions
- Web applications integrating ChatterMate chat functionality
Discovery Timeline
- 2026-01-24 - CVE CVE-2026-24399 published to NVD
- 2026-01-26 - Last updated in NVD database
Technical Details for CVE-2026-24399
Vulnerability Analysis
This vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting. The ChatterMate chatbot framework fails to implement proper input validation and output encoding for user-supplied chat messages. When a malicious payload is submitted through the chat interface, it is processed and rendered without sanitization, allowing the injected code to execute in the context of the victim's browser session.
The attack requires user interaction, as a victim must view or interact with chat content containing the malicious payload. However, once executed, the injected JavaScript has full access to the DOM and can exfiltrate sensitive information such as authentication tokens stored in localStorage or session cookies.
Root Cause
The root cause of this vulnerability lies in the inadequate input sanitization mechanisms within the ChatterMate chat processing pipeline. The framework accepts raw HTML and JavaScript content as chat input without proper encoding or filtering, allowing dangerous elements like <iframe> tags with javascript: URIs to be processed and executed in the client browser. This represents a fundamental failure in implementing secure input handling practices.
Attack Vector
The attack is conducted over the network, where an attacker crafts a malicious chat message containing HTML/JavaScript payloads. Specifically, an <iframe> element with a javascript: URI scheme can be injected through the chat input field. When another user views this malicious chat content, the JavaScript payload executes in their browser context. This enables the attacker to:
- Access and exfiltrate localStorage tokens and authentication data
- Steal session cookies to hijack active sessions
- Perform actions on behalf of the victim user
- Redirect users to malicious external sites
- Modify the appearance and behavior of the web application
The vulnerability can be triggered through malicious iframe elements containing JavaScript URIs in chat input fields. When processed by the vulnerable ChatterMate versions, these payloads execute in the victim's browser, enabling access to sensitive client-side storage such as localStorage and cookies. For detailed technical information, see the GitHub Security Advisory.
Detection Methods for CVE-2026-24399
Indicators of Compromise
- Chat messages containing <iframe>, <script>, or other HTML elements with javascript: URI schemes
- Unexpected outbound network requests from user browsers to external domains
- Anomalous access patterns to localStorage or cookie data
- JavaScript console errors indicating attempted XSS payload execution
Detection Strategies
- Implement Content Security Policy (CSP) headers to detect and block inline script execution
- Monitor web application logs for chat inputs containing suspicious HTML tags and JavaScript URIs
- Deploy browser-based XSS detection tools to identify injection attempts in real-time
- Utilize SentinelOne Singularity XDR to detect anomalous browser behavior and data exfiltration attempts
Monitoring Recommendations
- Enable detailed logging for all chat input processing events
- Configure alerts for CSP violation reports indicating blocked XSS attempts
- Monitor authentication token usage for signs of session hijacking
- Track user session anomalies that may indicate compromised credentials
How to Mitigate CVE-2026-24399
Immediate Actions Required
- Upgrade ChatterMate to version 1.0.9 or later immediately
- Audit existing chat history for potential malicious payloads
- Invalidate and rotate authentication tokens for users who may have been exposed
- Review and strengthen Content Security Policy headers on all deployments
Patch Information
The ChatterMate development team has addressed this vulnerability in version 1.0.9. The fix implements proper input sanitization to prevent HTML and JavaScript injection through chat input fields. Organizations should upgrade to the patched version immediately.
- GitHub Release v1.0.9 - Official patched release
- GitHub Commit Changes - Security fix commit
- GitHub Security Advisory GHSA-72p3-w95w-q3j4 - Official advisory
Workarounds
- Implement server-side input validation to strip HTML tags and JavaScript from chat messages
- Deploy a Web Application Firewall (WAF) with XSS protection rules
- Enable strict Content Security Policy headers to block inline script execution
- Consider disabling chat functionality until the upgrade can be completed
# Example Content Security Policy header configuration
# Add to web server configuration to help mitigate XSS attacks
Content-Security-Policy: default-src 'self'; script-src 'self'; frame-src 'none'; object-src 'none'
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
