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4.3 Medium

CVE-2026-55653 Openssh: double free in red hat enterprise linux versions of openssh dh-gex client path during fips known-group validation leads to client-side denial of service

Description

A flaw was found in OpenSSH. A malicious SSH server can exploit a double free vulnerability in the Diffie-Hellman Group Exchange (DH-GEX) client path. This occurs during FIPS (Federal Information Processing Standards) mode known-group validation when the client processes attacker-controlled DH-GEX group parameters. Successful exploitation leads to client-side process termination, resulting in a Denial of Service (DoS).

CVSS 3.1 detail

Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L

Exploitable remotely over the network, without an account and if a user takes an action; the impact on data or service is limited.

Attack vector
Network
Attack complexity
Low
Privileges required
None
Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

Affected products and versions

Product Affected versions Fixed in
Red Hat Enterprise Linux 10 Versions not published
Red Hat Enterprise Linux 6 Versions not published
Red Hat Enterprise Linux 7 Versions not published
Red Hat Enterprise Linux 8 Versions not published
Red Hat Enterprise Linux 9 Versions not published
Red Hat Hardened Images 10.3 earliest → < 10.3p1-6.hum1 10.3p1-6.hum1
Red Hat OpenShift Container Platform 4 Versions not published
Red Hat Update Infrastructure 5 1787241260 earliest → < 1787241260 1787241260
Red Hat Enterprise Linux 10.0 Extended Update Support Versions not published
Show the 9 other branches
Product Affected versions Fixed in
Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions Versions not published
Red Hat Enterprise Linux 9.6 Extended Update Support Versions not published
Red Hat OpenShift AI 3.4 1791885505 earliest → < 1791885505 1791885505
Red Hat OpenShift AI 3.0 1793042072 earliest → < 1793042072 1793042072
Red Hat OpenShift AI 3.2 1791818512 earliest → < 1791818512 1791818512
Red Hat OpenShift AI 3.3 1791818877 earliest → < 1791818877 1791818877
Red Hat OpenShift AI 3.5 1791819104 earliest → < 1791819104 1791819104
Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions Versions not published
Red Hat OpenShift Container Platform 5 Versions not published

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