CriticalVulnerability

CVE-2026-43899: DeepChat arbitrary protocol execution through native pop-up window handlers

Source: NVD(opens in a new tab)
Identifier: CVE-2026-43899
Published: May 11, 2026
Record updated: October 9, 2026

Known exploitation: Not listed in the CISA Known Exploited Vulnerabilities catalog at the last check.
EPSS: 0.4%

Summary

CVE-2026-43899 affects DeepChat, an open-source AI agent platform, prior to v1.0.4-beta.1. An incomplete fix for CVE-2025-55733 left native Electron pop-up window handlers unsanitized, so a malicious Markdown link with target="_blank" can route a URL through tabPresenter.ts directly to shell.openExternal(url), bypassing the isValidExternalUrl check. A compromised AI endpoint or attacker can trigger this, enabling arbitrary protocol execution.

Mitigation

Fixed in v1.0.4-beta.1.

Details

Scores and exploitation

CVSS score: 9.6(critical)
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Attack vector: network
Attack complexity: low
Privileges required: none
User interaction: required
EPSS: 0.4%Estimated probability that this CVE is exploited in the next 30 days, from the FIRST Exploit Prediction Scoring System. Read on November 7, 2026.
Disclosure date: May 11, 2026

Weaknesses and techniques

Weakness (CWE): CWE-20

Classification

Attack type: Other
Attack sophistication: Moderate
AI component targeted: Agent
Impact: Confidentiality,
Integrity,
Availability
Labels: security

How this record was produced

Summaries, mitigations and labels on this page are generated automatically from the source. The linked source is authoritative. The source gives this advisory a description and no title, so the title above is a headline generated from the source text.

Original source: https://nvd.nist.gov/vuln/detail/CVE-2026-43899

First tracked: May 12, 2026 at 02:12 AM ET, from NVD/CVE Database

Classifier: claude-haiku-5-5, prompt v4

Classifier confidence: 90% (self-assessed)

Summary

Mitigation

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