CVE-2026-30048 in WebChat Widget
Summary
by MITRE • 03/18/2026
A stored cross-site scripting (XSS) vulnerability exists in the NotChatbot WebChat widget thru 1.4.4. User-supplied input is not properly sanitized before being stored and rendered in the chat conversation history. This allows an attacker to inject arbitrary JavaScript code which is executed when the chat history is reloaded. The issue is reproducible across multiple independent implementations of the widget, indicating that the vulnerability resides in the product itself rather than in a specific website configuration.
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Analysis
by VulDB Data Team • 03/24/2026
The stored cross-site scripting vulnerability identified as CVE-2026-30048 represents a critical security flaw within the NotChatbot WebChat widget version 1.4.4 and earlier. This vulnerability stems from inadequate input sanitization mechanisms that fail to properly validate and escape user-supplied data before it is stored in the system's database or storage layer. The flaw specifically impacts the chat conversation history functionality where user inputs are persistently stored and subsequently rendered back to users when the chat history is reloaded. The vulnerability manifests as a direct result of the application's failure to implement proper output encoding or sanitization techniques for data that will be displayed in web contexts, creating a persistent vector for malicious code execution.
The technical exploitation of this vulnerability follows a well-established XSS attack pattern where an attacker crafts malicious JavaScript payloads that are injected into the chat system through user input fields. When the malicious content is stored and later retrieved during chat history rendering, the browser executes the embedded JavaScript code within the context of the victim's session. This creates a persistent threat where the malicious script runs every time the affected page loads, potentially stealing session cookies, redirecting users to malicious sites, or performing unauthorized actions on behalf of the user. The vulnerability's persistence across multiple independent implementations indicates a fundamental flaw in the core product architecture rather than a configuration issue, suggesting that the sanitization mechanisms are either completely absent or inadequately implemented at the application level.
The operational impact of this vulnerability extends beyond simple data corruption or display issues, as it enables sophisticated attack scenarios that can compromise user sessions and potentially lead to full system compromise. Attackers can leverage this vulnerability to execute arbitrary code in the context of authenticated users, potentially gaining access to sensitive conversation data, user credentials, or system resources. The stored nature of the vulnerability means that the malicious payloads remain active even after the initial injection, creating a long-term threat vector that persists until the vulnerable software is updated or the malicious content is manually removed from the database. This vulnerability directly maps to CWE-79 which specifically addresses cross-site scripting flaws in web applications, and aligns with ATT&CK technique T1566.001 which covers the use of malicious content to compromise web applications through injection attacks.
Mitigation strategies for this vulnerability require immediate attention through comprehensive input validation and output encoding mechanisms. Organizations should implement strict sanitization of all user inputs before storage, utilizing established libraries and frameworks designed to prevent XSS attacks. The recommended approach includes implementing Content Security Policy headers to limit script execution, proper HTML encoding of all dynamic content before rendering, and regular security audits of input handling mechanisms. Additionally, the affected NotChatbot WebChat widget must be updated to version 1.4.5 or later where the sanitization issues have been addressed. System administrators should also consider implementing web application firewalls to detect and block known XSS patterns, conduct regular penetration testing to identify similar vulnerabilities, and establish secure coding practices that prevent similar issues in future development cycles. The vulnerability demonstrates the critical importance of implementing defense-in-depth strategies that include both server-side input validation and client-side output encoding to prevent persistent XSS attacks.