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Alerts This Week
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Fedora OpenSSH Serious Denial of Service and Heap Vulnerabilities Issues

fedora
Calendar Grey July 8, 2026
Dist Fedora Esm H88
Critical advisories for Fedora OpenSSH address denial of service and heap overflow issues for 2026 updates.
Improve GSS KEX algorithms documentation CVE-2026-55653: Fix double free in openssh DH-GEX client path during FIPS known- group validation that leads to client-side denial of servi...

Summary

SSH (Secure SHell) is a program for logging into and executing

commands on a remote machine. SSH is intended to replace rlogin and

rsh, and to provide secure encrypted communications between two

untrusted hosts over an insecure network. X11 connections and

arbitrary TCP/IP ports can also be forwarded over the secure channel.

OpenSSH is OpenBSD's version of the last free version of SSH, bringing

it up to date in terms of security and features.

This package includes the core files necessary for both the OpenSSH

client and server. To make this package useful, you should also

install openssh-clients, openssh-server, or both.

Update Information:

Improve GSS KEX algorithms documentation CVE-2026-55653: Fix double free in openssh DH-GEX client path during FIPS known- group validation that leads to client-side denial of service CVE-2026-55654: Fix heap out-of-bounds read during GSSAPI indicator cleanup due to missing NULL terminator CVE-2026-55655: Fix MITM of X11 forwarding via abstract UNIX socket pre-binding

Topics%20covered

Topics Covered

security advisory denial of service fedora critical heap overflow openssh

Change Log

* Tue Jul 7 2026 Dmitry Belyavskiy - 10.2p1-12 - Improve GSS KEX algorithms documentation Patches are submitted by xspielinbox+redhat@protonmail.com Resolves: rhbz#2241564 * Tue Jul 7 2026 Zoltan Fridrich - 10.2p1-11 - CVE-2026-55653: Fix double free in openssh DH-GEX client path during FIPS known-group validation that leads to client-side denial of service - CVE-2026-55654: Fix heap out-of-bounds read during GSSAPI indicator cleanup due to missing NULL terminator - CVE-2026-55655: Fix MITM of X11 forwarding via abstract UNIX socket pre-binding - Remove duplicate manpage entries from ssh(1) Resolves: rhbz#2442505

References


[ 1 ] Bug #2241564 - KexAlgorithms accepts gss-* algorithms in certain cases, but it is completely unclear what this does https://bugzilla.redhat.com/show_bug.cgi?id=2241564 [ 2 ] Bug #2442505 - 0043-openssh-8.7p1-ssh-manpage.patch introduces duplicates in documentation https://bugzilla.redhat.com/show_bug.cgi?id=2442505

Update Instructions

This update can be installed with the "dnf" update program. Use su -c 'dnf upgrade --advisory FEDORA-2026-a80275b42d' at the command line. For more information, refer to the dnf documentation available at http://dnf.readthedocs.io/en/latest/command_ref.html#upgrade-command-label

Severity
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Name: openssh
Product: Fedora 44
Version: 10.2p1
Release: 12.fc44
URL: http://www.openssh.com/portable.html
Summary: An open source implementation of SSH protocol version 2

Topics%20covered

Topics Covered

security advisory denial of service fedora critical heap overflow openssh

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