Claude Desktop: SSH Host Key Verification Bypass Allows Man-in-the-Middle Attack on Remote Sessions
The Claude Desktop app gives you Claude Code with a graphical interface built for running multiple sessions side by side. From 1.2581.0 to before 1.4304.0, Claude Desktop's SSH remote development feature verified only whether a hostname existed in ~/.ssh/known_hosts without comparing the server's presented host key against the stored key. This allowed a network-positioned attacker to present an arbitrary SSH host key and have the connection silently accepted, enabling a man-in-the-middle attack on remote development sessions. Successful exploitation required the attacker to be in a network position to intercept SSH traffic (e.g., via ARP spoofing, rogue Wi-Fi, or DNS poisoning) and the target hostname to already have an entry in the victim's known_hosts file. This vulnerability is fixed in 1.4304.0.
Problem Types
| Type | CWE ID | Description |
|---|
| CWE | CWE-297 | CWE-297: Improper Validation of Certificate with Host Mismatch |
| CWE | CWE-322 | CWE-322: Key Exchange without Entity Authentication |
Type: CWE
Description: CWE-297: Improper Validation of Certificate with Host Mismatch
Type: CWE
Description: CWE-322: Key Exchange without Entity Authentication
Metrics
| Version | Base score | Base severity | Vector |
|---|
| 4.0 | 7.4 | HIGH | CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N |
Version: 4.0
Base score: 7.4
Base severity: HIGH
Vector: CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N