CVE-2026-55653
Fixed in a distro release EPSS <1%CVSS 4.3
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).
Products: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions, Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions, Red Hat Enterprise Linux 9.6 Extended Update Support, Red Hat Hardened Images, Red Hat OpenShift AI 3.0, Red Hat OpenShift AI 3.2, Red Hat OpenShift AI 3.3, Red Hat OpenShift AI 3.4, Red Hat OpenShift AI 3.5, Red Hat Update Infrastructure 5, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat OpenShift Container Platform 4
Distro releases
| Release | Package | Fixed in |
|---|---|---|
| AlmaLinux 10 | openssh | 9.9p1-25.el10_2.alma.1 |
| AlmaLinux 10 | openssh-askpass | 9.9p1-25.el10_2.alma.1 |
| AlmaLinux 10 | openssh-clients | 9.9p1-25.el10_2.alma.1 |
| AlmaLinux 10 | openssh-keycat | 9.9p1-25.el10_2.alma.1 |
| AlmaLinux 10 | openssh-keysign | 9.9p1-25.el10_2.alma.1 |
| AlmaLinux 10 | openssh-server | 9.9p1-25.el10_2.alma.1 |
| AlmaLinux 8 | openssh | 8.0p1-30.el8_10 |
| AlmaLinux 8 | openssh-askpass | 8.0p1-30.el8_10 |
| AlmaLinux 8 | openssh-cavs | 8.0p1-30.el8_10 |
| AlmaLinux 8 | openssh-clients | 8.0p1-30.el8_10 |
| AlmaLinux 8 | openssh-keycat | 8.0p1-30.el8_10 |
| AlmaLinux 8 | openssh-ldap | 8.0p1-30.el8_10 |
| AlmaLinux 8 | openssh-server | 8.0p1-30.el8_10 |
| AlmaLinux 8 | pam_ssh_agent_auth | 0.10.3-7.30.el8_10 |
| AlmaLinux 9 | openssh | 9.9p1-9.el9_8.alma.1 |
| AlmaLinux 9 | openssh-askpass | 9.9p1-9.el9_8.alma.1 |
| AlmaLinux 9 | openssh-clients | 9.9p1-9.el9_8.alma.1 |
| AlmaLinux 9 | openssh-keycat | 9.9p1-9.el9_8.alma.1 |
| AlmaLinux 9 | openssh-server | 9.9p1-9.el9_8.alma.1 |
| AlmaLinux 9 | pam_ssh_agent_auth | 0.10.4-7.9.el9_8.alma.1 |
| Debian 11 | openssh | no fix |
| Debian 12 | openssh | no fix |
| Debian 13 | openssh | no fix |
| Debian 14 | openssh | no fix |
| Red Hat Enterprise Linux 10.2 | openssh | 0:9.9p1-25.el10_2 |
| Red Hat Enterprise Linux 10.2 | openssh-askpass | 0:9.9p1-25.el10_2 |
| Red Hat Enterprise Linux 10.2 | openssh-askpass-debuginfo | 0:9.9p1-25.el10_2 |
| Red Hat Enterprise Linux 10.2 | openssh-clients | 0:9.9p1-25.el10_2 |
| Red Hat Enterprise Linux 10.2 | openssh-clients-debuginfo | 0:9.9p1-25.el10_2 |
| Red Hat Enterprise Linux 10.2 | openssh-debuginfo | 0:9.9p1-25.el10_2 |
| Red Hat Enterprise Linux 10.2 | openssh-debugsource | 0:9.9p1-25.el10_2 |
| Red Hat Enterprise Linux 10.2 | openssh-keycat | 0:9.9p1-25.el10_2 |
| Red Hat Enterprise Linux 10.2 | openssh-keycat-debuginfo | 0:9.9p1-25.el10_2 |
| Red Hat Enterprise Linux 10.2 | openssh-keysign | 0:9.9p1-25.el10_2 |
| Red Hat Enterprise Linux 10.2 | openssh-keysign-debuginfo | 0:9.9p1-25.el10_2 |
| Red Hat Enterprise Linux 10.2 | openssh-server | 0:9.9p1-25.el10_2 |
| Red Hat Enterprise Linux 10.2 | openssh-server-debuginfo | 0:9.9p1-25.el10_2 |
| Red Hat Enterprise Linux 10.2 | openssh-sk-dummy-debuginfo | 0:9.9p1-25.el10_2 |
| Red Hat Enterprise Linux 8 | openssh | 0:8.0p1-30.el8_10 |
| Red Hat Enterprise Linux 8 | openssh-askpass | 0:8.0p1-30.el8_10 |
| Red Hat Enterprise Linux 8 | openssh-askpass-debuginfo | 0:8.0p1-30.el8_10 |
| Red Hat Enterprise Linux 8 | openssh-cavs | 0:8.0p1-30.el8_10 |
| Red Hat Enterprise Linux 8 | openssh-cavs-debuginfo | 0:8.0p1-30.el8_10 |
| Red Hat Enterprise Linux 8 | openssh-clients | 0:8.0p1-30.el8_10 |
| Red Hat Enterprise Linux 8 | openssh-clients-debuginfo | 0:8.0p1-30.el8_10 |
| Red Hat Enterprise Linux 8 | openssh-debuginfo | 0:8.0p1-30.el8_10 |
| Red Hat Enterprise Linux 8 | openssh-debugsource | 0:8.0p1-30.el8_10 |
| Red Hat Enterprise Linux 8 | openssh-keycat | 0:8.0p1-30.el8_10 |
| Red Hat Enterprise Linux 8 | openssh-keycat-debuginfo | 0:8.0p1-30.el8_10 |
| Red Hat Enterprise Linux 8 | openssh-ldap | 0:8.0p1-30.el8_10 |
| Red Hat Enterprise Linux 8 | openssh-ldap-debuginfo | 0:8.0p1-30.el8_10 |
| Red Hat Enterprise Linux 8 | openssh-server | 0:8.0p1-30.el8_10 |
| Red Hat Enterprise Linux 8 | openssh-server-debuginfo | 0:8.0p1-30.el8_10 |
| Red Hat Enterprise Linux 8 | pam_ssh_agent_auth | 0:0.10.3-7.30.el8_10 |
| Red Hat Enterprise Linux 8 | pam_ssh_agent_auth-debuginfo | 0:0.10.3-7.30.el8_10 |
| Red Hat Enterprise Linux 9 | openssh | 0:9.9p1-9.el9_8 |
| Red Hat Enterprise Linux 9 | openssh-askpass | 0:9.9p1-9.el9_8 |
| Red Hat Enterprise Linux 9 | openssh-askpass-debuginfo | 0:9.9p1-9.el9_8 |
| Red Hat Enterprise Linux 9 | openssh-clients | 0:9.9p1-9.el9_8 |
| Red Hat Enterprise Linux 9 | openssh-clients-debuginfo | 0:9.9p1-9.el9_8 |
| Red Hat Enterprise Linux 9 | openssh-debuginfo | 0:9.9p1-9.el9_8 |
| Red Hat Enterprise Linux 9 | openssh-debugsource | 0:9.9p1-9.el9_8 |
| Red Hat Enterprise Linux 9 | openssh-keycat | 0:9.9p1-9.el9_8 |
| Red Hat Enterprise Linux 9 | openssh-keycat-debuginfo | 0:9.9p1-9.el9_8 |
| Red Hat Enterprise Linux 9 | openssh-server | 0:9.9p1-9.el9_8 |
| Red Hat Enterprise Linux 9 | openssh-server-debuginfo | 0:9.9p1-9.el9_8 |
| Red Hat Enterprise Linux 9 | openssh-sk-dummy-debuginfo | 0:9.9p1-9.el9_8 |
| Red Hat Enterprise Linux 9 | pam_ssh_agent_auth | 0:0.10.4-7.9.el9_8 |
| Red Hat Enterprise Linux 9 | pam_ssh_agent_auth-debuginfo | 0:0.10.4-7.9.el9_8 |
| Red Hat Enterprise Linux eus 10.0 | openssh | 0:9.9p1-7.el10_0.5 |
| Red Hat Enterprise Linux eus 10.0 | openssh-askpass | 0:9.9p1-7.el10_0.5 |
| Red Hat Enterprise Linux eus 10.0 | openssh-clients | 0:9.9p1-7.el10_0.5 |
| Red Hat Enterprise Linux eus 10.0 | openssh-keycat | 0:9.9p1-7.el10_0.5 |
| Red Hat Enterprise Linux eus 10.0 | openssh-keysign | 0:9.9p1-7.el10_0.5 |
| Red Hat Enterprise Linux eus 10.0 | openssh-server | 0:9.9p1-7.el10_0.5 |
| Red Hat hummingbird 1 | openssh | 0:10.3p1-6.hum1 |
| Red Hat hummingbird 1 | openssh-askpass | 0:10.3p1-6.hum1 |
| Red Hat hummingbird 1 | openssh-clients | 0:10.3p1-6.hum1 |
| Red Hat hummingbird 1 | openssh-keycat | 0:10.3p1-6.hum1 |
| Red Hat hummingbird 1 | openssh-keysign | 0:10.3p1-6.hum1 |
| Red Hat hummingbird 1 | openssh-server | 0:10.3p1-6.hum1 |
| Red Hat hummingbird 1 | openssh-sk-dummy | 0:10.3p1-6.hum1 |
| Red Hat rhel e4s 9.4 | openssh-clients | 0:8.7p1-38.el9_4.10 |
| Red Hat rhel e4s 9.4 | openssh-server | 0:8.7p1-38.el9_4.10 |
| Red Hat rhel eus 9.6 | openssh | 0:8.7p1-45.el9_6.5 |
| Red Hat rhel eus 9.6 | openssh-askpass | 0:8.7p1-45.el9_6.5 |
| Red Hat rhel eus 9.6 | openssh-clients | 0:8.7p1-45.el9_6.5 |
| Red Hat rhel eus 9.6 | openssh-keycat | 0:8.7p1-45.el9_6.5 |
| Red Hat rhel eus 9.6 | openssh-server | 0:8.7p1-45.el9_6.5 |
| Red Hat rhel eus 9.6 | pam_ssh_agent_auth | 0:0.10.4-5.45.el9_6.5 |
| Rocky Linux 10 | openssh | 0:9.9p1-25.el10_2.rocky.0.1 |
| Rocky Linux 8 | openssh | 0:8.0p1-30.el8_10 |
| Rocky Linux 9 | openssh | 0:9.9p1-9.el9_8.rocky.0.1 |
| Ubuntu 18.04 LTS | openssh-ssh1 | no fix |
| Ubuntu 20.04 LTS | openssh-ssh1 | no fix |
| Ubuntu 22.04 LTS | openssh-ssh1 | no fix |
| Ubuntu 24.04 LTS | openssh-ssh1 | no fix |
| Ubuntu 25.10 | openssh-ssh1 | no fix |
| Ubuntu 26.04 LTS | openssh-ssh1 | no fix |
| Ubuntu 26.10 | openssh-ssh1 | no fix |
| Ubuntu Pro 14.04 LTS | openssh | no fix |
| Ubuntu Pro 16.04 LTS | openssh | no fix |
| Ubuntu Pro 18.04 LTS | openssh | no fix |
| Ubuntu Pro 20.04 LTS | openssh | no fix |
| Ubuntu Pro FIPS-preview 22.04 LTS | openssh | no fix |
| Ubuntu Pro FIPS-updates 16.04 LTS | openssh | no fix |
| Ubuntu Pro FIPS-updates 18.04 LTS | openssh | no fix |
| Ubuntu Pro FIPS-updates 20.04 LTS | openssh | no fix |
| Ubuntu Pro FIPS-updates 22.04 LTS | openssh | no fix |
| Ubuntu Pro FIPS-updates 24.04 LTS | openssh | no fix |
| Ubuntu Pro FIPS 16.04 LTS | openssh | no fix |
| Ubuntu Pro FIPS 18.04 LTS | openssh | no fix |
| Ubuntu Pro FIPS 20.04 LTS | openssh | no fix |