Which versions are affected by CVE-2024-6387?

Affected: OpenSSH 8.5p1 – 9.7p1 (glibc Linux). Fixed in: OpenSSH 9.8p1+.

criticalCVSS 8.1/10·Published: 2024-07-01·OpenSSH

How to fix CVE-2024-6387 – Step-by-Step Guide

CVE-2024-6387 (OpenSSH regreSSHion – Unauthenticated RCE) is a CRITICAL severity vulnerability with a CVSS score of 8.1/10. A signal handler race condition in OpenSSH's server (sshd) allows unauthenticated remote code execution as root on glibc-based Linux systems. Affects OpenSSH 8.5p1–9.7p1. Follow the step-by-step guide below to remediate this vulnerability in your infrastructure.

CVE ID

CVE-2024-6387

Severity

CRITICAL

CVSS Score

8.1/10

Affected

OpenSSH

What is OpenSSH regreSSHion – Unauthenticated RCE?

OpenSSH regreSSHion – Unauthenticated RCE (CVE-2024-6387) affects OpenSSH. A signal handler race condition in OpenSSH's server (sshd) allows unauthenticated remote code execution as root on glibc-based Linux systems. Affects OpenSSH 8.5p1–9.7p1. It was published on 2024-07-01 and affects OpenSSH 8.5p1 – 9.7p1 (glibc Linux). The fixed version is OpenSSH 9.8p1+.

Affected Versions

OpenSSH 8.5p1 – 9.7p1 (glibc Linux)

Fixed In

OpenSSH 9.8p1+

Official References

Impact and Risks for your Infrastructure

Full root compromise of the affected SSH server. An attacker can execute arbitrary code without any authentication, gaining complete control of the system.

opensshrcecriticallinux2024

Step-by-Step Mitigation Guide

To remediate CVE-2024-6387, follow the prioritized mitigation steps: Upgrade OpenSSH to 9.8p1 or later immediately. → Restrict SSH access via firewall: allow only trusted IPs on port 22. → Enable fail2ban or equivalent rate-limiting to slow exploitation attempts. → Set LoginGraceTime 0 in sshd_config as a temporary workaround (disables grace period). → Audit SSH server logs for exploitation attempts (look for connection floods). → Consider moving SSH to a non-standard port or VPN-only access (Tailscale, WireGuard).. Verify the fix using the verification commands below and confirm the patched version is deployed across all affected systems.

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).

Frequently Asked Questions

What is the CVSS score for CVE-2024-6387?▼

CVE-2024-6387 has a CVSS score of 8.1/10 (critical severity). This reflects the most severe potential impact, requiring immediate remediation.

Which versions of OpenSSH are affected?▼

Affected: OpenSSH 8.5p1 – 9.7p1 (glibc Linux). The vulnerability was fixed in: OpenSSH 9.8p1+.

How long does it take to fix CVE-2024-6387?▼

For most teams: 15–60 minutes to apply the patch, plus 15 minutes of post-patch verification. Complex multi-service environments may require 2–4 hours including staging validation.

Is CVE-2024-6387 being actively exploited?▼

Check the NVD entry and CISA KEV catalog for exploitation status. As a critical-severity vulnerability, treat it as a priority remediation regardless of known exploitation status.

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This CVE fix guide is based on publicly available security advisories (NVD, vendor bulletins). Always test changes in a staging environment before applying to production. Verify against the official vendor advisory for the most up-to-date guidance.