How to fix CVE-2024-6387 – Step-by-Step Guide
CVE-2024-6387, dubbed "regreSSHion," is a critical unauthenticated remote code execution vulnerability affecting OpenSSH servers. Published on July 1, 2024, it carries a CVSS score of 8.1. This flaw allows attackers to compromise vulnerable systems without authentication.
What is OpenSSH regreSSHion – Unauthenticated RCE?
This vulnerability stems from a signal handler race condition within the OpenSSH server (sshd) process. Exploiting this race condition allows an unauthenticated attacker to achieve remote code execution. Specifically, it targets glibc-based Linux systems running OpenSSH versions 8.5p1 through 9.7p1.
Impact and Risks for your Infrastructure
A successful exploit of CVE-2024-6387 results in a full root compromise of the affected SSH server. Attackers gain the ability to execute arbitrary code with root privileges, leading to complete control over the compromised system. This poses a severe risk to infrastructure integrity and data security.
Step-by-Step Mitigation Guide
To mitigate CVE-2024-6387, immediately upgrade your OpenSSH server to version 9.8p1 or later. After upgrading, verify the installed version using `ssh -V` to confirm the fix is applied. Regularly monitor for further security updates.
- 1Upgrade OpenSSH to 9.8p1 or later immediately.
- 2Restrict SSH access via firewall: allow only trusted IPs on port 22.
- 3Enable fail2ban or equivalent rate-limiting to slow exploitation attempts.
- 4Set LoginGraceTime 0 in sshd_config as a temporary workaround (disables grace period).
- 5Audit SSH server logs for exploitation attempts (look for connection floods).
- 6Consider moving SSH to a non-standard port or VPN-only access (Tailscale, WireGuard).