--- id: CVE-2026-55653 title: A flaw was found in OpenSSH summary: >- 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 va… severity: medium cvss: 4.3 cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L' cwe: - CWE-415 vendor: openbsd product: openssh affected: - openssh - hardened_images - openshift_container_platform = 4.0 - enterprise_linux = 6.0 - enterprise_linux = 7.0 - enterprise_linux = 8.0 - enterprise_linux = 9.0 - enterprise_linux = 10.0 patched: - enterprise_linux_appstream_eus_v_10_0 - enterprise_linux_appstream_v_10 - enterprise_linux_appstream_v_8 - enterprise_linux_appstream_v_9 - enterprise_linux_baseos_eus_v_10_0 - enterprise_linux_baseos_v_10 - enterprise_linux_baseos_v_8 - enterprise_linux_baseos_e4s_v_9_4 - enterprise_linux_baseos_v_9 - hardened_images - update_infrastructure 5 published: '2026-06-23' updated: '2026-10-14' sourceUpdated: '2026-10-14T20:17:49.213' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-55653' references: - url: 'https://access.redhat.com/errata/RHSA-2026:36759' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:47755' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:47756' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:47757' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:54387' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:58981' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:76748' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:76993' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:80513' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82749' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82750' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82751' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82752' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82753' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82754' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82755' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82756' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82757' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82758' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82759' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82761' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82762' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82763' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82897' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82898' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82899' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82900' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82901' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82902' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82903' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82904' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82907' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82908' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82909' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82910' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82912' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82913' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82914' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82915' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82916' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82917' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82918' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82920' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82921' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82922' label: secalert@redhat.com - url: 'https://access.redhat.com/errata/RHSA-2026:82923' label: secalert@redhat.com - url: 'https://access.redhat.com/security/cve/CVE-2026-55653' label: secalert@redhat.com - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2462351' label: secalert@redhat.com - url: >- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-55653.json - url: 'https://www.cve.org/CVERecord?id=CVE-2026-55653' - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-55653' - url: 'https://access.redhat.com/errata/RHSA-2026:89739' label: 'RHSA-2026:89739' tags: - nvd - cve.org - csaf - vex - red-hat epss: 0.0053 epssPercentile: 0.44594 ssvc: exploitation: none automatable: 'no' technicalImpact: partial timestamp: '2026-06-23T14:30:51.025049Z' ingestedAt: '2026-08-24T13:03:31.720Z' --- ## Overview 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). ## Affected - `openssh` - `hardened_images` - `openshift_container_platform = 4.0` - `enterprise_linux = 6.0` - `enterprise_linux = 7.0` - `enterprise_linux = 8.0` - `enterprise_linux = 9.0` - `enterprise_linux = 10.0` ## Remediation Refer to the linked advisories for vendor-supplied fixes and affected version ranges. ## Vendor advisories - **RHSA-2026:76748** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v. 10.0), Red Hat Enterprise Linux BaseOS EUS (v. 10.0) · released 2026-10-06 · [advisory](https://access.redhat.com/errata/RHSA-2026:76748) - **RHSA-2026:47757** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10) · released 2026-07-30 · [advisory](https://access.redhat.com/errata/RHSA-2026:47757) - **RHSA-2026:47755** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8), Red Hat Enterprise Linux BaseOS (v. 8) · released 2026-07-30 · [advisory](https://access.redhat.com/errata/RHSA-2026:47755) - **RHSA-2026:47756** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux BaseOS (v. 9) · released 2026-07-29 · [advisory](https://access.redhat.com/errata/RHSA-2026:47756) - **RHSA-2026:76993** · Red Hat · fixed in: Red Hat Enterprise Linux BaseOS E4S (v.9.4) · released 2026-10-07 · [advisory](https://access.redhat.com/errata/RHSA-2026:76993) - **RHSA-2026:36759** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-07-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:36759) - **RHSA-2026:54387** · Red Hat · fixed in: Red Hat Update Infrastructure 5 · released 2026-08-12 · [advisory](https://access.redhat.com/errata/RHSA-2026:54387) - **RHSA-2026:58981** · Red Hat · fixed in: Red Hat Update Infrastructure 5 · released 2026-08-24 · [advisory](https://access.redhat.com/errata/RHSA-2026:58981) - **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat OpenShift Container Platform 4, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7 · updated 2026-10-26 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-55653.json) - **RHSA-2026:80513** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v.9.6), Red Hat Enterprise Linux BaseOS EUS (v.9.6) · released 2026-10-12 · [advisory](https://access.redhat.com/errata/RHSA-2026:80513) - **RHSA-2026:82749** · Red Hat · fixed in: Red Hat OpenShift AI 3.4 · released 2026-10-14 · [advisory](https://access.redhat.com/errata/RHSA-2026:82749) - **RHSA-2026:89739** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream E4S (v.9.2), Red Hat Enterprise Linux BaseOS E4S (v.9.2) · released 2026-10-26 · [advisory](https://access.redhat.com/errata/RHSA-2026:89739) - **RHSA-2026:82761** · Red Hat · fixed in: Red Hat OpenShift AI 3.0 · released 2026-10-14 · [advisory](https://access.redhat.com/errata/RHSA-2026:82761) - **RHSA-2026:82751** · Red Hat · fixed in: Red Hat OpenShift AI 3.0 · released 2026-10-14 · [advisory](https://access.redhat.com/errata/RHSA-2026:82751) - **RHSA-2026:82914** · Red Hat · fixed in: Red Hat OpenShift AI 3.0 · released 2026-10-14 · [advisory](https://access.redhat.com/errata/RHSA-2026:82914)