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How CVE-2025-42921 Works
The vulnerability exists in JetBrains Toolbox App versions before 2.6 due to missing host key verification in its SSH plugin. When establishing SSH connections, the plugin fails to validate the remote host’s cryptographic key, enabling Man-in-the-Middle (MitM) attacks. Attackers can intercept or modify SSH traffic between the client and server, leading to unauthorized access, data leaks, or code execution. The absence of key verification allows attackers to spoof legitimate hosts, making users unknowingly connect to malicious servers.
DailyCVE Form
Platform: JetBrains Toolbox App
Version: < 2.6
Vulnerability: Missing SSH host verification
Severity: Critical
Date: 04/17/2025
What Undercode Say:
Exploitation Analysis
- Attack Vector: Network-based MitM
- Prerequisites: Attacker must intercept SSH traffic (e.g., via ARP spoofing or rogue Wi-Fi).
- Impact: Credential theft, session hijacking, or malware delivery.
Exploit Command Example (Simulated MitM)
arpspoof -i eth0 -t <target_ip> <gateway_ip> ssh -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null user@spoofed_host
Protection Measures
- Update: Upgrade to JetBrains Toolbox App 2.6 or later.
2. Manual Verification: Enforce SSH host key checks:
echo "Host " >> ~/.ssh/config echo " StrictHostKeyChecking yes" >> ~/.ssh/config
3. Network Hardening: Use VPNs or SSH over TLS (e.g., ssh -J proxy.example.com).
Detection Script (Bash)
!/bin/bash TOOLBOX_VERSION=$(jetbrains-toolbox --version | cut -d' ' -f2) if [[ "$TOOLBOX_VERSION" < "2.6" ]]; then echo "Vulnerable: CVE-2025-42921 detected." else echo "Patched." fi
Mitigation via Firewall Rules
iptables -A OUTPUT -p tcp --dport 22 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT iptables -A INPUT -p tcp --sport 22 -m conntrack --ctstate ESTABLISHED -j ACCEPT iptables -A OUTPUT -p tcp --dport 22 -j DROP Block unverified SSH
References
- JetBrains Advisory
- CWE-295: Improper Certificate Validation
- CVSS 4.0: 9.3 (Critical) AV:N/AC:L/AT:N/PR:N/UI:N/S:C/C:H/I:H/A:H
Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
Undercode
