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).
CVE-2026-55653
CVSS base score
4.3 (v3.1)
Severity
MEDIUM
Attack vector
Network
Weakness
CWE-415
Last modified
October 30, 2026
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
Affected products
openbsd openssh
redhat hardened images
redhat openshift container platform
redhat enterprise linux