Public vulnerability disclosure
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
publishedCWE-415
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).
Technical severity4.3 mediumCVSS 3.1 · CNA: redhat
Published2026-06-23Source updated 2026-11-05
Collected2026-11-052 attributed sources
Fixes and workarounds
Workaround
To mitigate this issue, OpenSSH clients operating in FIPS mode should avoid negotiating the `diffie-hellman-group-exchange-sha256` key exchange algorithm. This can be achieved by explicitly listing allowed key exchange algorithms in the client's SSH configuration file (e.g., `/etc/ssh/ssh_config` or `~/.ssh/config`), ensuring `diffie-hellman-group-exchange-sha256` is *not* included. For example, to use a subset of common algorithms, you might configure: ``` KexAlgorithms [email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group14-sha1 ``` (Note: The above example `KexAlgorithms` list is illustrative and should be adjusted based on your environment's security requirements.) Additionally, avoid using non-fatal client flows, such as `ssh-keyscan`, against untrusted SSH servers while FIPS mode is enabled. Changes to `ssh_config` will take effect for new SSH connections.
Source: CNA: redhatAffected products and versions
| Product | Versions | Authority |
|---|---|---|
| Red Hat Enterprise Linux 10 Red Hat openssh
https://access.redhat.com/downloads/content/package-browser/ |
≥ 0:9.9p1-25.el10_2; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 10.0 Extended Update Support Red Hat openssh
https://access.redhat.com/downloads/content/package-browser/ |
≥ 0:9.9p1-7.el10_0.5; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 8 Red Hat openssh
https://access.redhat.com/downloads/content/package-browser/ |
≥ 0:8.0p1-30.el8_10; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 9 Red Hat openssh
https://access.redhat.com/downloads/content/package-browser/ |
≥ 0:9.9p1-9.el9_8; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions Red Hat openssh
https://access.redhat.com/downloads/content/package-browser/ |
≥ 0:8.7p1-30.el9_2.13; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions Red Hat openssh
https://access.redhat.com/downloads/content/package-browser/ |
≥ 0:8.7p1-38.el9_4.10; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 9.6 Extended Update Support Red Hat openssh
https://access.redhat.com/downloads/content/package-browser/ |
≥ 0:8.7p1-45.el9_6.5; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat Hardened Images Red Hat openssh-main
https://catalog.redhat.com/software/containers/ |
≥ 10.3p1-6.hum1; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.0 Red Hat rhai/base-image-cuda-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818590; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.0 Red Hat rhai/base-image-cpu-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818589; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.0 Red Hat rhai/base-image-spyre-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818505; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.0 Red Hat rhai/base-image-tpu-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818496; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.0 Red Hat rhai/base-image-rocm-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818502; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.0 Red Hat rhai/base-image-cpu-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1793042072; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.2 Red Hat rhai/base-image-spyre-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818602; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.2 Red Hat rhai/base-image-cpu-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818598; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.2 Red Hat rhai/base-image-tpu-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818512; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.2 Red Hat rhai/base-image-cuda-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818587; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.2 Red Hat rhai/base-image-rocm-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818778; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.2 Red Hat rhai/base-image-rocm-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818512; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.3 Red Hat rhai/base-image-tpu-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818782; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.3 Red Hat rhai/base-image-rocm-6.4-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818782; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.3 Red Hat rhai/base-image-cuda-12.9-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818627; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.3 Red Hat rhai/base-image-rocm-7.0-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818790; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.3 Red Hat rhai/base-image-cpu-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818874; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.3 Red Hat rhai/base-image-neuron-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818792; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.3 Red Hat rhai/base-image-cuda-13.0-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818662; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.3 Red Hat rhai/base-image-spyre-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818877; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.4 Red Hat rhai/base-image-neuron-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791883722; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.4 Red Hat rhai/base-image-cuda-12.9-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791881612; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.4 Red Hat rhai/base-image-cpu-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791885618; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.4 Red Hat rhai/base-image-rocm-6.4-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791881487; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.4 Red Hat rhai/base-image-spyre-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791881732; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.4 Red Hat rhai/base-image-rocm-7.1-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791883315; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.4 Red Hat rhai/base-image-gaudi-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791881486; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.4 Red Hat rhai/base-image-tpu-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791881769; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.4 Red Hat rhai/base-image-cuda-13.0-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791885505; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.5 Red Hat rhai/base-image-spyre-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791819252; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.5 Red Hat rhai/base-image-gaudi-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818749; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.5 Red Hat rhai/base-image-cpu-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791819206; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.5 Red Hat rhai/base-image-neuron-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818979; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.5 Red Hat rhai/base-image-rocm-7.14-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791819123; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.5 Red Hat rhai/base-image-tpu-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791818901; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.5 Red Hat rhai/base-image-rubin-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791820333; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.5 Red Hat rhai/base-image-cuda-13.0-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791819495; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift AI 3.5 Red Hat rhai/base-image-cuda-12.9-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1791819104; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat Update Infrastructure 5 Red Hat rhui5/installer-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1786435483; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat Update Infrastructure 5 Red Hat rhui5/rhua-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1786533529; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat Update Infrastructure 5 Red Hat rhui5/installer-tp-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1787135742; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat Update Infrastructure 5 Red Hat rhui5/rhua-tp-rhel9
https://catalog.redhat.com/software/containers/ |
≥ 1787241260; < * (unaffected, rpm)
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 6 Red Hat openssh
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 7 Red Hat openssh
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift Container Platform 4 Red Hat openshift/ose-rhel-coreos-8
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift Container Platform 4 Red Hat openshift/ose-rhel-coreos-9
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift Container Platform 5 Red Hat openshift/ose-rhel-coreos-9
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 4.3 medium |
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L | CNA: redhat |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://access.redhat.com/errata/RHSA-2026:36759CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:47755CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:47756CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:47757CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:54387CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:58981CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:76748CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:76993CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:80513CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82749CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82750CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82751CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82752CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82753CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82754CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82755CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82756CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82757CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82758CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82759CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82761CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82762CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82763CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82897CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82898CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82899CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82900CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82901CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82902CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82903CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82904CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82907CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82908CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82909CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82910CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82912CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82913CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82914CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82915CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82916CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82917CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82918CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82920CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82921CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82922CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:82923CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:89739CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:91232CNA: redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2026-55653CNA: redhat · vdb-entry, x_refsource_REDHAT
- https://bugzilla.redhat.com/show_bug.cgi?id=2462351CNA: redhat · issue-tracking, x_refsource_REDHAT
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