---
title: "CVE-2024-6387: Openssh: regresshion - race condition in ssh allows rce/dos"
url: https://erroneo.us/security/cve/CVE-2024-6387/
description: "CVE-2024-6387 (OpenSSH): A security regression (CVE-2006-5051) was discovered in OpenSSH's server (sshd). There is a race condition which can lead sshd to…"
type: vulnerability-record
section: "Security Digest"
date_published: 2024-07-01
date_modified: 2026-10-21
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2024-6387"
kev: false
cvss: 8.1
epss: 0.99506
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2024-6387: Openssh: regresshion - race condition in ssh allows rce/dos

**Signal:** High exploit likelihood. EPSS ranks it in the top 5% of all CVEs for likely exploitation in the next 30 days. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 99.5% , percentile 99.9: FIRST’s model estimates a 99.5% chance of exploitation activity in the next 30 days, higher than 99.9% of all scored CVEs (very high). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Editorial verdict: Patch this week. regreSSHion: OpenSSH sshd Signal Race RCE (CVE-2024-6387) — Serious on paper (unauthenticated root RCE in sshd), but the only demonstrated exploit needed a 32-bit glibc target and 6-8 hours of continuous connections in a lab, so patch promptly through your distro instead of panicking.

## What it is

A security regression (CVE-2006-5051) was discovered in OpenSSH's server (sshd). There is a race condition which can lead sshd to handle some signals in an unsafe manner. An unauthenticated, remote attacker may be able to trigger it by failing to authenticate within a set time period.

## Affected products (CVE record)

-  OpenSSH: 8.5p1 <= 9.7p1
- Red Hat Red Hat Enterprise Linux 9: see advisory
- Red Hat Red Hat Enterprise Linux 9: see advisory
- Red Hat Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions: see advisory
- Red Hat Red Hat Enterprise Linux 9.2 Extended Update Support: see advisory
- Red Hat Red Hat OpenShift Container Platform 4.13: see advisory
- Red Hat Red Hat OpenShift Container Platform 4.14: see advisory
- Red Hat Red Hat OpenShift Container Platform 4.15: see advisory
- Red Hat Red Hat OpenShift Container Platform 4.16: see advisory
- Red Hat Red Hat Ceph Storage 5: see advisory

## Severity

- redhat CVSS 3.1: 8.1 `CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 99.51% probability of exploitation activity in the next 30 days; percentile 99.9.

## Sources

- [RHSA-2024:4312](https://access.redhat.com/errata/RHSA-2024:4312)
- [RHSA-2024:4340](https://access.redhat.com/errata/RHSA-2024:4340)
- [RHSA-2024:4389](https://access.redhat.com/errata/RHSA-2024:4389)
- [RHSA-2024:4469](https://access.redhat.com/errata/RHSA-2024:4469)
- [RHSA-2024:4474](https://access.redhat.com/errata/RHSA-2024:4474)
- [RHSA-2024:4479](https://access.redhat.com/errata/RHSA-2024:4479)
- [RHSA-2024:4484](https://access.redhat.com/errata/RHSA-2024:4484)
- [CVE.org record CVE-2024-6387](https://www.cve.org/CVERecord?id=CVE-2024-6387)
- [NVD entry CVE-2024-6387](https://nvd.nist.gov/vuln/detail/CVE-2024-6387)
- [access.redhat.com](https://access.redhat.com/security/cve/CVE-2024-6387)
- [RHBZ#2294604](https://bugzilla.redhat.com/show_bug.cgi?id=2294604)
- [santandersecurityresearch.github.io](https://santandersecurityresearch.github.io/blog/sshing_the_masses.html)
- [openssh.com](https://www.openssh.com/txt/release-9.8)
- [qualys.com](https://www.qualys.com/2024/07/01/cve-2024-6387/regresshion.txt)
- [vicarius.io](https://www.vicarius.io/vsociety/posts/regresshion-an-openssh-regression-error-cve-2024-6387)
- [exploit-db.com](https://www.exploit-db.com/exploits/52269)
- [packetstorm.news](https://packetstorm.news/files/id/190587/)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/01/12)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/01/13)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/02/1)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/03/1)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/03/11)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/03/2)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/03/3)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/03/4)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/03/5)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/04/1)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/04/2)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/08/2)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/08/3)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/09/2)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/09/5)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/10/1)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/10/2)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/10/3)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/10/4)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/10/6)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/11/1)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/11/3)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/23/4)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/23/6)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/28/2)
- [openwall.com](http://www.openwall.com/lists/oss-security/2024/07/28/3)
- [archlinux.org](https://archlinux.org/news/the-sshd-service-needs-to-be-restarted-after-upgrading-to-openssh-98p1/)
- [arstechnica.com](https://arstechnica.com/security/2024/07/regresshion-vulnerability-in-openssh-gives-attackers-root-on-linux/)
- [blog.qualys.com](https://blog.qualys.com/vulnerabilities-threat-research/2024/07/01/regresshion-remote-unauthenticated-code-execution-vulnerability-in-openssh-server)
- [explore.alas.aws.amazon.com](https://explore.alas.aws.amazon.com/CVE-2024-6387.html)
- [forum.vmssoftware.com](https://forum.vmssoftware.com/viewtopic.php?f=8&t=9132)
- [ftp.netbsd.org](https://ftp.netbsd.org/pub/NetBSD/security/advisories/NetBSD-SA2024-002.txt.asc)
- [github.com](https://github.com/AlmaLinux/updates/issues/629)
- [github.com](https://github.com/Azure/AKS/issues/4379)
- [github.com](https://github.com/PowerShell/Win32-OpenSSH/discussions/2248)
- [github.com](https://github.com/PowerShell/Win32-OpenSSH/issues/2249)
- [github.com](https://github.com/microsoft/azurelinux/issues/9555)
- [github.com](https://github.com/openela-main/openssh/commit/e1f438970e5a337a17070a637c1b9e19697cad09)
- [github.com](https://github.com/oracle/oracle-linux/issues/149)
- [github.com](https://github.com/rapier1/hpn-ssh/issues/87)
- [github.com](https://github.com/zgzhang/cve-2024-6387-poc)
- [lists.almalinux.org](https://lists.almalinux.org/archives/list/announce@lists.almalinux.org/thread/23BF5BMGFVEVUI2WNVAGMLKT557EU7VY/)
- [lists.mindrot.org](https://lists.mindrot.org/pipermail/openssh-unix-announce/2024-July/000158.html)
- [lists.mindrot.org](https://lists.mindrot.org/pipermail/openssh-unix-dev/2024-July/041431.html)
- [news.ycombinator.com](https://news.ycombinator.com/item?id=40843778)
- [psirt.global.sonicwall.com](https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2024-0010)
- [security-tracker.debian.org](https://security-tracker.debian.org/tracker/CVE-2024-6387)
- [security.netapp.com](https://security.netapp.com/advisory/ntap-20240701-0001/)
- [sig-security.rocky.page](https://sig-security.rocky.page/issues/CVE-2024-6387/)
- [stackdiary.com](https://stackdiary.com/openssh-race-condition-in-sshd-allows-remote-code-execution/)
- [ubuntu.com](https://ubuntu.com/security/CVE-2024-6387)
- [ubuntu.com](https://ubuntu.com/security/notices/USN-6859-1)
- [akamai.com](https://www.akamai.com/blog/security-research/2024-openssh-vulnerability-regression-what-to-know-and-do)
- [arista.com](https://www.arista.com/en/support/advisories-notices/security-advisory/19904-security-advisory-0100)
- [freebsd.org](https://www.freebsd.org/security/advisories/FreeBSD-SA-24:04.openssh.asc)
- [splunk.com](https://www.splunk.com/en_us/blog/security/cve-2024-6387-regresshion-vulnerability.html)
- [suse.com](https://www.suse.com/security/cve/CVE-2024-6387.html)
- [theregister.com](https://www.theregister.com/2024/07/01/regresshion_openssh/)
- [support.apple.com](https://support.apple.com/kb/HT214119)
- [support.apple.com](https://support.apple.com/kb/HT214118)
- [support.apple.com](https://support.apple.com/kb/HT214120)
- [seclists.org](http://seclists.org/fulldisclosure/2024/Jul/20)
- [seclists.org](http://seclists.org/fulldisclosure/2024/Jul/18)
- [seclists.org](http://seclists.org/fulldisclosure/2024/Jul/19)
- [cert-portal.siemens.com](https://cert-portal.siemens.com/productcert/html/ssa-446545.html)
- [cert-portal.siemens.com](https://cert-portal.siemens.com/productcert/html/ssa-082556.html)

---
Source page: https://erroneo.us/security/cve/CVE-2024-6387/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt