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Vulnerability record · CVE-2026-43899 · published 11 May 2026

CVE-2026-43899: Improper input validation vulnerability

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.

9.6 CVSS 3.1 Critical EPSS 0.56% · top 55.7% CWE-20 · Improper input validation Deferred
9.6CVSS 3.1 base score
0.56%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

Description

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

References

LinkTags
https://github.com/ThinkInAIXYZ/deepchat/security/advisories/GHSA-cp8j-jx7q-7r5f
https://github.com/ThinkInAIXYZ/deepchat/security/advisories/GHSA-cp8j-jx7q-7r5f

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Source: NIST National Vulnerability Database (record CVE-2026-43899), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.