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CVE-2024-6387

Openssh: regresshion - race condition in ssh allows rce/dos

publishedCWE-364

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.

Technical severity8.1 highCVSS 3.1 · CNA: redhat
Published2024-07-01Source updated 2026-11-06
Collected2026-11-062 attributed sources

Fixes and workarounds

Workaround

The below process can protect against a Remote Code Execution attack by disabling the LoginGraceTime parameter on Red Hat Enterprise Linux 9. However, the sshd server is still vulnerable to a Denial of Service if an attacker exhausts all the connections. 1) As root user, open the /etc/ssh/sshd_config 2) Add or edit the parameter configuration: ~~~ LoginGraceTime 0 ~~~ 3) Save and close the file 4) Restart the sshd daemon: ~~~ systemctl restart sshd.service ~~~ Setting LoginGraceTime to 0 disables the SSHD server's ability to drop connections if authentication is not completed within the specified timeout. If this mitigation is implemented, it is highly recommended to use a tool like 'fail2ban' alongside a firewall to monitor log files and manage connections appropriately. If any of the mitigations mentioned above is used, please note that the removal of LoginGraceTime parameter from sshd_config is not automatic when the updated package is installed.

Source: CNA: redhat

Affected products and versions

ProductVersionsAuthority


OpenSSH
https://www.openssh.com/ 		≥ 8.5p1; ≤ 9.7p1 (affected, custom)
Other versions: unaffected 		CNA: redhat
Red Hat Enterprise Linux 9
Red Hat
openssh
https://access.redhat.com/downloads/content/package-browser/ 		≥ 0:8.7p1-38.el9_4.1; < * (unaffected, rpm)
Other versions: affected 		CNA: redhat
Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions
Red Hat
openssh
https://access.redhat.com/downloads/content/package-browser/ 		≥ 0:8.7p1-12.el9_0.1; < * (unaffected, rpm)
Other versions: affected 		CNA: redhat
Red Hat Enterprise Linux 9.2 Extended Update Support
Red Hat
openssh
https://access.redhat.com/downloads/content/package-browser/ 		≥ 0:8.7p1-30.el9_2.4; < * (unaffected, rpm)
Other versions: affected 		CNA: redhat
Red Hat OpenShift Container Platform 4.13
Red Hat
openshift/ose-rhel-coreos-9
https://catalog.redhat.com/software/containers/ 		≥ 413.92.202407091321-0; < * (unaffected, rpm)
Other versions: affected 		CNA: redhat
Red Hat OpenShift Container Platform 4.14
Red Hat
openshift/ose-rhel-coreos-9
https://catalog.redhat.com/software/containers/ 		≥ 414.92.202407091253-0; < * (unaffected, rpm)
Other versions: affected 		CNA: redhat
Red Hat OpenShift Container Platform 4.15
Red Hat
openshift/ose-rhel-coreos-9
https://catalog.redhat.com/software/containers/ 		≥ 415.92.202407091355-0; < * (unaffected, rpm)
Other versions: affected 		CNA: redhat
Red Hat OpenShift Container Platform 4.16
Red Hat
openshift/ose-rhel-coreos-9
https://catalog.redhat.com/software/containers/ 		≥ 416.94.202407081958-0; < * (unaffected, rpm)
Other versions: affected 		CNA: redhat
Red Hat Ceph Storage 5
Red Hat
openssh
https://access.redhat.com/downloads/content/package-browser/ 		Range not reported
Other versions: unaffected 		CNA: redhat
Red Hat Ceph Storage 6
Red Hat
openssh
https://access.redhat.com/downloads/content/package-browser/ 		Range not reported
Other versions: unaffected 		CNA: redhat
Red Hat Ceph Storage 7
Red Hat
openssh
https://access.redhat.com/downloads/content/package-browser/ 		Range not reported
Other versions: unaffected 		CNA: redhat
Red Hat Enterprise Linux 10
Red Hat
openssh
https://access.redhat.com/downloads/content/package-browser/ 		Range not reported
Other versions: unaffected 		CNA: redhat
Red Hat Enterprise Linux 6
Red Hat
openssh
https://access.redhat.com/downloads/content/package-browser/ 		Range not reported
Other versions: unaffected 		CNA: redhat
Red Hat Enterprise Linux 7
Red Hat
openssh
https://access.redhat.com/downloads/content/package-browser/ 		Range not reported
Other versions: unaffected 		CNA: redhat
Red Hat Enterprise Linux 8
Red Hat
openssh
https://access.redhat.com/downloads/content/package-browser/ 		Range not reported
Other versions: unaffected 		CNA: redhat
Red Hat OpenShift Container Platform 4
Red Hat
openshift/ose-rhel-coreos-8
https://access.redhat.com/downloads/content/package-browser/ 		Range not reported
Other versions: affected 		CNA: redhat
Industrial Edge Management OS (IEM-OS)
Siemens 		≥ 0; < * (affected, custom)
Other versions: unknown 		ADP: siemens-SADP
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
Siemens 		≥ V3.1.5; < * (affected, custom)
Other versions: unknown 		ADP: siemens-SADP
SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
Siemens 		≥ V3.1.5; < * (affected, custom)
Other versions: unknown 		ADP: siemens-SADP
SINAMICS IIoT module
Siemens 		≥ 0; < V1.0 HF1 (affected, custom)
Other versions: unknown 		ADP: siemens-SADP
SINEMA Remote Connect Server
Siemens 		≥ 0; < V3.2 SP2 (affected, custom)
Other versions: unknown 		ADP: siemens-SADP
SINUMERIK ONE
Siemens 		≥ 0; < V6.24 (affected, custom)
Other versions: unknown 		ADP: siemens-SADP
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
Siemens 		≥ V3.1.5; < * (affected, custom)
Other versions: unknown 		ADP: siemens-SADP

Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.

CVSS assessments

Version / scoreVectorAuthority
3.1 / 8.1
high		 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:HCNA: redhat

Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

References

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