Recently, OpenSSH fixed a remote code execution vulnerability (CVE-2024-6387). The vulnerability was caused by a race condition in the signal handling process of the OpenSSH server (sshd), allowing unauthenticated attackers to execute arbitrary code as root on Linux systems. Currently, technical details of this vulnerability (including proof of concept code, PoC) have been publicly disclosed on the Internet. Users affected by this vulnerability are advised to upgrade to the latest version as soon as possible to fix the issue.
Affected Versions#
- OpenSSH < 4.4p1
- 8.5p1 <= OpenSSH < 9.8p1
Fix Target#
OpenSSH >= 9.8p1
Fix Process#
Check OpenSSH: Release Notes
Choose 9.8p1.
Check the currently installed version. If unable to run the dnf command, replace dnf with yum
dnf list installed openssh
Check the currently running version
ssh -V
Check available versions with the package manager
dnf list available openssh
If OpenSSH >= 9.8p1 is not satisfied, download and install from OpenSSH
wget https://cloudflare.cdn.openbsd.org/pub/OpenBSD/OpenSSH/portable/openssh-9.8p1.tar.gz
Unpack
tar -xzf openssh-9.8p1.tar.gz
cd openssh-9.8p1
Check the current installation directory
which sshd && which ssh
Location /usr/bin/ssh
Adjust the prefix parameter in the following commands based on the installation location:
sudo ./configure --prefix=/usr
Then
make
sudo make install
Check for updates
ls -l /usr/bin/ssh
ls -l /usr/sbin/sshd
Check the current version
ssh -V
Update completed.
If connected to Linux via SSH, do not disconnect. Use a new terminal to connect to Linux once. If the connection is successful, then disconnect. If unable to connect, troubleshoot further.