CVE-2026-23733 in lobe-chat
Summary
by MITRE • 01/19/2026
LobeChat is an open source chat application platform. Prior to version 2.0.0-next.180, a stored Cross-Site Scripting (XSS) vulnerability in the Mermaid artifact renderer allows attackers to execute arbitrary JavaScript within the application context. This XSS can be escalated to Remote Code Execution (RCE) by leveraging the exposed `electronAPI` IPC bridge, allowing attackers to run arbitrary system commands on the victim's machine. Version 2.0.0-next.180 patches the issue.
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Analysis
by VulDB Data Team • 01/19/2026
The vulnerability identified as CVE-2026-23733 affects LobeChat, an open source chat application platform that has gained significant traction in developer communities for its extensible architecture and markdown rendering capabilities. This security flaw resides within the Mermaid artifact renderer component that processes diagramming content submitted by users. The affected version range prior to 2.0.0-next.180 demonstrates a critical oversight in input sanitization and output encoding mechanisms that directly impacts the application's security posture. The vulnerability represents a sophisticated attack vector that combines multiple exploit techniques to achieve elevated privileges within the application environment.
The technical implementation of this vulnerability stems from inadequate sanitization of user-provided input within the Mermaid rendering engine. When users submit Mermaid diagram code containing malicious payloads, the application fails to properly escape or filter special characters that could be interpreted as executable JavaScript code. This stored XSS vulnerability occurs because the rendered output is directly inserted into the DOM without proper context-aware escaping mechanisms. The flaw specifically manifests when the Mermaid renderer processes diagrams that contain embedded script tags or other malicious constructs that bypass standard security filters. The vulnerability is classified as a CWE-79 - Cross-Site Scripting, which represents one of the most common and dangerous web application security flaws according to the CWE catalog.
The operational impact of this vulnerability extends far beyond typical XSS limitations through a sophisticated exploitation chain that leverages Electron's IPC (Inter-Process Communication) bridge mechanism. Attackers can first establish a stored XSS payload within the Mermaid rendering context, which then executes within the application's Electron environment. The electronAPI IPC bridge exposes privileged system capabilities to the renderer process, creating a direct pathway for attackers to escalate from client-side script execution to full system command execution. This escalation demonstrates a critical design flaw where application sandboxing and privilege separation are insufficiently enforced. The vulnerability enables remote attackers to execute arbitrary system commands with the privileges of the user running the LobeChat application, potentially leading to complete system compromise.
The exploitation of this vulnerability aligns with ATT&CK technique T1059.007 - Command and Scripting Interpreter: JavaScript, where attackers leverage JavaScript execution capabilities to gain further control. The attack chain begins with crafting malicious Mermaid diagrams containing JavaScript payloads, followed by successful storage within the application's data persistence layer, and concludes with execution through the electronAPI IPC bridge. This vulnerability also maps to ATT&CK technique T1566.001 - Phishing: Spearphishing Attachment, as attackers may deliver malicious diagrams through social engineering campaigns. The combination of stored XSS with IPC bridge exploitation creates a particularly dangerous attack vector that bypasses traditional web application security controls.
Security mitigations for this vulnerability should begin with immediate patching to version 2.0.0-next.180 or later, which includes proper input sanitization and output encoding mechanisms for the Mermaid renderer. Organizations should implement comprehensive input validation that filters or escapes all potentially dangerous characters and constructs within diagram code. The application architecture should enforce stricter sandboxing of rendering components to prevent IPC bridge access from untrusted content. Additionally, implementing Content Security Policy headers and proper CORS configuration can provide additional defense-in-depth measures. Regular security audits of third-party libraries and rendering components should be conducted to identify similar vulnerabilities. The incident highlights the importance of secure coding practices for Electron applications and the critical need for proper privilege separation between application components. Network segmentation and monitoring for unusual system command execution patterns can provide early detection of exploitation attempts, while user education about the risks of executing untrusted code in development environments remains essential for overall security posture.