CVE-2026-55653
A flaw was found in OpenSSH.
Published Jun 23, 2026 · updated Oct 14, 2026 · openbsd openssh
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).
Timeline
Detection, updates, and resolution for this record.
Jun 23, 2026 · NIST NVD
Detected
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 De
Oct 14, 2026 · NIST NVD
Updated
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 De
Oct 14, 2026 · NIST NVD
Updated
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 De
Affected
- cpe openbsd/opensshversion unspecified
- cpe redhat/enterprise linux10.0
- cpe redhat/enterprise linux6.0
- cpe redhat/enterprise linux7.0
- cpe redhat/enterprise linux8.0
- cpe redhat/enterprise linux9.0
- cpe redhat/hardened imagesversion unspecified
- cpe redhat/openshift container platform4.0
Sources
- CVE.orgCVE-2026-55653
Official CVE identifier
cve.org - FIRST EPSSCVE-2026-55653
30-day exploitation probability 0.6%
first.org - NIST NVDCVE-2026-55653
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
nvd.nist.gov