Moderate Security Vulnerability in OpenSSH Packages on AlmaLinux
Summary
ALSA-2026:47755: Moderate: openssh security update. Affects openssh versions < 8.0p1-30.el8_10. Fixed in 8.0p1-30.el8_10. How to fix ↓
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Background
OpenSSH is a widely used implementation of the SSH (Secure Shell) protocol, providing secure access to remote systems. It is essential for secure communications in Linux, UNIX, and similar operating systems. The OpenSSH suite includes various components such as the OpenSSH client, server, and associated tools, which are critical for secure file transfers and remote command execution. However, vulnerabilities in OpenSSH can lead to severe security risks, including unauthorized access and denial of service.
Vulnerability Detail
The vulnerability stems from two critical issues in the OpenSSH implementation on AlmaLinux. The first issue (CVE-2026-55655) allows for a local Man-in-the-Middle (MITM) attack on X11 forwarding via abstract UNIX socket pre-binding, which could enable an attacker to intercept and manipulate X11 traffic. The second issue (CVE-2026-55653) involves a double free error during FIPS known-group validation in the DH-GEX client path, leading to a potential client-side denial of service. These vulnerabilities can compromise the integrity and availability of the OpenSSH service.
How To Fix
Minimum fixed version
8.0p1-30.el8_10
This is the first release that contains the fix.
sudo dnf update opensshTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, users can disable X11 forwarding in their SSH configurations until the packages are updated. This can be done by modifying the SSH configuration file (usually located at /etc/ssh/sshd_config) and setting the following directive:
X11Forwarding no
After making this change, restart the SSH service with:
sudo systemctl restart sshd
Conclusion
In summary, the OpenSSH packages on AlmaLinux have been identified with moderate security vulnerabilities that could lead to serious security risks. It is crucial for users to update their packages to the latest patched versions to safeguard their systems. Temporary workarounds are available, but applying the updates is the best course of action.
See every vulnerability recorded for openssh →
FAQ
OpenSSH is a suite of secure networking utilities based on the SSH protocol, allowing secure remote access and file transfers.
The vulnerabilities can lead to unauthorized access, data interception, and denial of service, compromising system security.
You can use Vulert, which monitors and alerts for open-source vulnerabilities in your software. Visit Vulert Scanner to check your application without signup.
As a temporary measure, disable X11 forwarding in your SSH configuration to mitigate the risk until you can apply the update.
Detailed information can be found on the CVE pages for CVE-2026-55653 and CVE-2026-55655, which provide insights into the vulnerabilities and their impacts.
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