CVE-2026-24399 is a critical cross-site scripting (XSS) vulnerability identified in the ChatterMate AI chatbot framework, specifically in versions 1.0.8 and earlier. ChatterMate allows users to interact with AI-driven chatbots without coding, making it popular for rapid deployment of conversational agents. The vulnerability arises from improper neutralization of input during web page generation (CWE-79), where the chatbot accepts and executes malicious HTML or JavaScript payloads embedded in chat inputs. Attackers can craft payloads using <iframe> elements with javascript: URIs that execute arbitrary scripts in the victim's browser context. This execution context allows attackers to access sensitive client-side data such as localStorage tokens and cookies, which can be used to hijack sessions, impersonate users, or perform further attacks. The vulnerability does not require authentication but does require user interaction (e.g., the victim engaging with the chatbot). The scope of impact is broad because any user interacting with a vulnerable chatbot instance can be targeted. The vulnerability has a CVSS 3.1 score of 9.3, reflecting its critical severity due to network attack vector, low complexity, no privileges required, user interaction needed, and high impact on confidentiality and integrity. Although no known exploits are reported in the wild yet, the ease of exploitation and the sensitive nature of data exposed make this a high-risk issue. The vendor has addressed the vulnerability in version 1.0.9 by properly sanitizing inputs and preventing execution of malicious scripts. Organizations using affected versions should upgrade immediately and review their chatbot deployment configurations to prevent exploitation.

For European organizations, this vulnerability poses a significant threat to confidentiality and integrity of client-side data. Organizations using ChatterMate chatbots in customer support, internal communications, or public-facing websites risk session hijacking, data theft, and unauthorized actions performed on behalf of users. This can lead to data breaches involving personal data protected under GDPR, resulting in legal and financial penalties. The vulnerability could also be leveraged for phishing or social engineering attacks by injecting deceptive content into chatbot responses. The lack of authentication requirement and low exploitation complexity increase the likelihood of attacks. Disruption of trust in AI chatbot services and potential reputational damage are additional concerns. Organizations in sectors such as finance, healthcare, and e-commerce, where sensitive data is frequently handled, are particularly vulnerable. The vulnerability could also be exploited to pivot to further attacks within internal networks if chatbots are integrated with backend systems.

1. Immediate upgrade of all ChatterMate chatbot instances to version 1.0.9 or later to apply the official patch. 2. Implement strict input validation and sanitization on all user-supplied data before rendering in chatbot responses, including disallowing iframe tags or javascript: URIs. 3. Deploy Content Security Policy (CSP) headers that restrict script execution sources and disallow inline scripts to reduce XSS risk. 4. Conduct regular security audits and penetration testing focused on chatbot interfaces and input handling. 5. Educate users and administrators about the risks of interacting with untrusted chatbot inputs and recognizing suspicious behavior. 6. Monitor chatbot logs for unusual input patterns or repeated injection attempts. 7. If upgrading is delayed, consider temporarily disabling chatbot features that accept free-form HTML or JavaScript input. 8. Review and limit chatbot permissions and data access to minimize impact if compromised. 9. Integrate Web Application Firewalls (WAF) with rules to detect and block XSS payloads targeting chatbot endpoints.