CVE-2026-43899: DeepChat: Incomplete Fix for CVE-2025-55733 leads to Remote Code Execution via Markdown Links bypassing `isValidExternalUrl`
DeepChat is an open-source artificial intelligence agent platform that unifies models, tools, and agents. Prior to v1.0.4-beta.1, An incomplete mitigation for CVE-2025-55733 leaves DeepChat vulnerable to an arbitrary protocol execution bypass (RCE). While the patch correctly restricted api.openExternal() inside the renderer's preload/index.ts script, it structurally neglected to sanitize native Electron pop-up window handlers. An attacker or a compromised AI endpoint returning a Markdown link can trigger a target="blank" native window interception in tabPresenter.ts, which forwards the malicious URL directly to shell.openExternal(url) and completely bypasses the isValidExternalUrl security boundary. This vulnerability is fixed in v1.0.4-beta.1.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-43899?
CVE-2026-43899 has been classified as a critical vulnerability due to its potential to allow remote code execution.
How do I fix CVE-2026-43899?
To mitigate CVE-2026-43899, upgrade DeepChat to version 1.0.4-beta.1 or later.
What types of systems are affected by CVE-2026-43899?
CVE-2026-43899 affects all versions of DeepChat prior to v1.0.4-beta.1.
What does CVE-2026-43899 exploit to execute malicious code?
CVE-2026-43899 exploits a bypass in Markdown links that allows remote code execution.
Is there a workaround for CVE-2026-43899?
No known workaround exists for CVE-2026-43899; upgrading to the latest version is the only solution.