Claude Desktop SSH Host Key Verification Bypass Vulnerability Allowing Man-in-the-Middle Attacks

A vulnerability in the Claude Desktop application, specifically in versions 1.2581.0 prior to 1.4304.0, allows for man-in-the-middle attacks during SSH remote development sessions. The issue arises because the application only checked if a hostname was listed in the known_hosts file, without verifying the server's presented host key against the stored key. This flaw enabled a network-positioned attacker to present an arbitrary SSH host key, which would be silently accepted, provided the target hostname already had an entry in the victim's known_hosts file. Exploitation required the attacker to intercept SSH traffic, such as through ARP spoofing, rogue Wi-Fi, or DNS poisoning.

Impact

Exploitation of this vulnerability could lead to unauthorized interception and manipulation of SSH traffic during remote development sessions, allowing an attacker to conduct a man-in-the-middle attack.

Remediation

Users of Claude Desktop who have the auto-update feature enabled have already received the patch for this vulnerability. Those who perform manual updates should upgrade to version 1.4304.0.