CVE-2006-5051

High [CVE-2006-5051 +1] regresshion - race condition in ssh allows rce/dos

CVE-2024-6387Source published Jul 1, 2024Source updated Jul 1, 2024

This bulletin covers 2 CVEs. The products, versions, score and guidance below describe the bulletin; check its source for applicability to this specific CVE.

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. Red Hat rates the severity of this flaw as Important for both Red Hat Enterprise Linux (RHEL) and OpenShift Container Platform (OCP). The most significant risk is Remote Code Execution, however this outcome requires significant resources to exploit. If mitigations are put in place, the consequences of exploitation are reduced. An attacker would then only be able to impact availability of the OpenSSH service. The main factor preventing a higher impact rating is an unpredictable race condition. All actively…

Affected products in this advisory

• Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions
• Red Hat Enterprise Linux 9.2 Extended Update Support
• Red Hat OpenShift Container Platform 4.13
• Red Hat OpenShift Container Platform 4.14

3 more entries in the full advisory.

Source-reported affected versions

Affected-version details not available in this record.

Source-reported fixed versions

• openssh-0:8.7p1-38.el9_4.1
• openssh-0:8.7p1-12.el9_0.1
• openssh-0:8.7p1-30.el9_2.4
• openshift/ose-rhel-coreos-9:413.92.202407091321-0

10 more entries in the full advisory.

Mitigation guidance

• 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.