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).
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Red Hat | Red Hat Enterprise Linux 10 | — | — |
| Red Hat | Red Hat Enterprise Linux 10.0 Extended Update Support | — | — |
| Red Hat | Red Hat Enterprise Linux 8 | — | — |
| Red Hat | Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | — | — |
| Red Hat | Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On | — | — |
| Red Hat | Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support | — | — |
| Red Hat | Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On | — | — |
| Red Hat | Red Hat Enterprise Linux 9 | — | — |
| Red Hat | Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions | — | — |
| Red Hat | Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions | — | — |
| Red Hat | Red Hat Enterprise Linux 9.6 Extended Update Support | — | — |
| Red Hat | Red Hat OpenShift Container Platform 4.13 | — | — |
| Red Hat | Red Hat Hardened Images | — | — |
| Red Hat | Red Hat OpenShift AI 3.0 | — | — |
| Red Hat | Red Hat OpenShift AI 3.2 | — | — |
| Red Hat | Red Hat OpenShift AI 3.3 | — | — |
| Red Hat | Red Hat OpenShift AI 3.4 | — | — |
| Red Hat | Red Hat OpenShift AI 3.5 | — | — |
| Red Hat | Red Hat Update Infrastructure 5 | — | — |
| Red Hat | Red Hat Enterprise Linux 6 | — | — |
| Red Hat | Red Hat Enterprise Linux 7 | — | — |
| Red Hat | Red Hat OpenShift Container Platform 4 | — | — |
| Red Hat | Red Hat OpenShift Container Platform 5 | — | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | openssh-ssh1 | No fix yet | — |
| Ubuntu 26.04 LTS | openssh-ssh1 | No fix yet | — |
| Ubuntu 25.10 | openssh-ssh1 | No fix yet | — |
| Ubuntu 24.04 LTS | openssh-ssh1 | No fix yet | — |
| Ubuntu 22.04 LTS | openssh-ssh1 | No fix yet | — |
Show 15 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | openssh-ssh1 | No fix yet | — |
| Ubuntu 18.04 LTS | openssh-ssh1 | No fix yet | — |
| Ubuntu Pro FIPS 20.04 LTS | openssh | No fix yet | — |
| Ubuntu Pro FIPS 18.04 LTS | openssh | No fix yet | — |
| Ubuntu Pro FIPS 16.04 LTS | openssh | No fix yet | — |
| Ubuntu Pro FIPS-updates 24.04 LTS | openssh | No fix yet | — |
| Ubuntu Pro FIPS-updates 22.04 LTS | openssh | No fix yet | — |
| Ubuntu Pro FIPS-updates 20.04 LTS | openssh | No fix yet | — |
| Ubuntu Pro FIPS-updates 18.04 LTS | openssh | No fix yet | — |
| Ubuntu Pro FIPS-updates 16.04 LTS | openssh | No fix yet | — |
| Ubuntu Pro FIPS-preview 22.04 LTS | openssh | No fix yet | — |
| Ubuntu Pro 20.04 LTS | openssh | No fix yet | — |
| Ubuntu Pro 18.04 LTS | openssh | No fix yet | — |
| Ubuntu Pro 16.04 LTS | openssh | No fix yet | — |
| Ubuntu Pro 14.04 LTS | openssh | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10 | openssh +5 | 9.9p1-25.el10_2 | RHSA-2026:47757 |
| RHEL 9 | openssh +4 | 9.9p1-9.el9_8 | RHSA-2026:47756 |
| RHEL 9 | pam_ssh_agent_auth | 0.10.4-7.9.el9_8 | RHSA-2026:47756 |
| RHEL 8 | openssh +6 | 8.0p1-30.el8_10 | RHSA-2026:47755 |
| RHEL 8 | pam_ssh_agent_auth | 0.10.3-7.30.el8_10 | RHSA-2026:47755 |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10.0 EUS | openssh +5 | 9.9p1-7.el10_0.5 | RHSA-2026:76748 |
| RHEL 9.6 EUS | openssh +4 | 8.7p1-45.el9_6.5 | RHSA-2026:80513 |
| RHEL 9.6 EUS | pam_ssh_agent_auth | 0.10.4-5.45.el9_6.5 | RHSA-2026:80513 |
| RHEL 9.4 E4S | openssh-server +1 | 8.7p1-38.el9_4.10 | RHSA-2026:76993 |
| Red Hat Hardened Images 1 | openssh +6 | 10.3p1-6.hum1 | RHSA-2026:36759 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | openssh +5 | 9.9p1-25.el10_2.alma.1 | ALSA-2026:47757 |
| AlmaLinux 9 | openssh +4 | 9.9p1-9.el9_8.alma.1 | ALSA-2026:47756 |
| AlmaLinux 9 | pam_ssh_agent_auth | 0.10.4-7.9.el9_8.alma.1 | ALSA-2026:47756 |
| AlmaLinux 8 | openssh +6 | 8.0p1-30.el8_10 | ALSA-2026:47755 |
| AlmaLinux 8 | pam_ssh_agent_auth | 0.10.3-7.30.el8_10 | ALSA-2026:47755 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 10 | openssh | 9.9p1-25.el10_2.rocky.0.1 | RLSA-2026:47757 |
| Rocky Linux 9 | openssh | 9.9p1-9.el9_8.rocky.0.1 | RLSA-2026:47756 |
| Rocky Linux 8 | openssh | 8.0p1-30.el8_10 | RLSA-2026:47755 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | openssh +4 | 9.9p1-10.amzn2023.0.1 | ALAS2023-2026-2031 |
| Amazon Linux 2023 | pam_ssh_agent_auth | 0.10.4-9.10.amzn2023.0.1 | ALAS2023-2026-2031 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | openssh | No fix yet | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 10 | openssh +5 | 9.9p1-25.0.1.el10_2 | ELSA-2026-47757 |
| Oracle Linux 9 | openssh +4 | 9.9p1-9.0.1.el9_8 | ELSA-2026-47756 |
| Oracle Linux 9 | pam_ssh_agent_auth | 0.10.4-7.9.0.1.el9_8 | ELSA-2026-47756 |
| Oracle Linux 8 | openssh +6 | 8.0p1-30.0.1.el8_10 | ELSA-2026-47755 |
| Oracle Linux 8 | pam_ssh_agent_auth | 0.10.3-7.30.0.1.el8_10 | ELSA-2026-47755 |
Advisories 19
- WID-SEC-2026-2039 OpenSSH: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 11, 2026
- ALSA-2026:47756 Important: openssh security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:47757 Important: openssh security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:47755 Moderate: openssh security update AlmaLinux Security Advisories · Oct 29, 2026
- RHSA-2026:80513 Red Hat Security Advisory: openssh security update Red Hat Security Advisories (RHSA) · Oct 17, 2026
- RHSA-2026:76993 Red Hat Security Advisory: openssh security update Red Hat Security Advisories (RHSA) · Oct 17, 2026
- RHSA-2026:76748 Red Hat Security Advisory: openssh security update Red Hat Security Advisories (RHSA) · Oct 17, 2026
- RHSA-2026:47757 Red Hat Security Advisory: openssh security update Red Hat Security Advisories (RHSA) · Oct 17, 2026
- RHSA-2026:47756 Red Hat Security Advisory: openssh security update Red Hat Security Advisories (RHSA) · Oct 17, 2026
- RHSA-2026:47755 Red Hat Security Advisory: openssh security update Red Hat Security Advisories (RHSA) · Oct 17, 2026
- RHSA-2026:36759 Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update Red Hat Security Advisories (RHSA) · Oct 15, 2026
- WID-SEC-2026-3043 IBM QRadar SIEM: Mehrere Schwachstellen BSI CERT-Bund (WID) · Sep 17, 2026
- ELSA-2026-47756 Important: openssh security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Aug 6, 2026
- ALAS2023-2026-2031 Moderate: openssh security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Aug 4, 2026
- ELSA-2026-47755 Moderate: openssh security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Jul 31, 2026
- RLSA-2026:47756 Important: openssh security update Rocky Linux Security Advisories · Jul 30, 2026
- RLSA-2026:47755 Moderate: openssh security update Rocky Linux Security Advisories · Jul 30, 2026
- RLSA-2026:47757 Important: openssh security update Rocky Linux Security Advisories · Jul 30, 2026
- ELSA-2026-47757 Important: openssh security update (Oracle Linux 10) Oracle Linux Security Advisories (ELSA) · Jul 30, 2026
References
- RHSA-2026:36759 vendor-advisory
- RHSA-2026:47755 vendor-advisory
- RHSA-2026:47756 vendor-advisory
- RHSA-2026:47757 vendor-advisory
- RHSA-2026:54387 vendor-advisory
- RHSA-2026:58981 vendor-advisory
- RHSA-2026:76748 vendor-advisory
- RHSA-2026:76993 vendor-advisory
- RHSA-2026:80513 vendor-advisory
- RHSA-2026:82749 vendor-advisory
- RHSA-2026:82750 vendor-advisory
- RHSA-2026:82751 vendor-advisory
- RHSA-2026:82752 vendor-advisory
- RHSA-2026:82753 vendor-advisory
- RHSA-2026:82754 vendor-advisory
- RHSA-2026:82755 vendor-advisory
- RHSA-2026:82756 vendor-advisory
- RHSA-2026:82757 vendor-advisory
- RHSA-2026:82758 vendor-advisory
- RHSA-2026:82759 vendor-advisory
- RHSA-2026:82761 vendor-advisory
- RHSA-2026:82762 vendor-advisory
- RHSA-2026:82763 vendor-advisory
- RHSA-2026:82897 vendor-advisory
- RHSA-2026:82898 vendor-advisory
- RHSA-2026:82899 vendor-advisory
- RHSA-2026:82900 vendor-advisory
- RHSA-2026:82901 vendor-advisory
- RHSA-2026:82902 vendor-advisory
- RHSA-2026:82903 vendor-advisory
- RHSA-2026:82904 vendor-advisory
- RHSA-2026:82907 vendor-advisory
- RHSA-2026:82908 vendor-advisory
- RHSA-2026:82909 vendor-advisory
- RHSA-2026:82910 vendor-advisory
- RHSA-2026:82912 vendor-advisory
- RHSA-2026:82913 vendor-advisory
- RHSA-2026:82914 vendor-advisory
- RHSA-2026:82915 vendor-advisory
- RHSA-2026:82916 vendor-advisory
- RHSA-2026:82917 vendor-advisory
- RHSA-2026:82918 vendor-advisory
- RHSA-2026:82920 vendor-advisory
- RHSA-2026:82921 vendor-advisory
- RHSA-2026:82922 vendor-advisory
- RHSA-2026:82923 vendor-advisory
- RHSA-2026:89739 vendor-advisory
- RHSA-2026:91232 vendor-advisory
- RHSA-2026:95745 vendor-advisory
- RHSA-2026:99573 vendor-advisory
- RHSA-2026:99592 vendor-advisory
- https://access.redhat.com/security/cve/CVE-2026-55653 vdb-entry
- RHBZ#2462351 issue-tracking