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Vulnerabilities

Vulnerability · CVE-2026-55653

A flaw was found in OpenSSH.

Published Jun 23, 2026 · catalog updated Oct 14, 2026 · A flaw was found

Check if you run it

No confirmed exploitation is on record for CVE-2026-55653. EPSS is 0.73%. Act only if a listed version of A flaw was found is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (A flaw was found).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium6.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.73%
Remediation
Not established
Affected products
cpe openbsd/openssh · cpe redhat/enterprise linux · cpe redhat/hardened images · cpe redhat/openshift container platform

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).

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • 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

How to fix CVE-2026-55653

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-55653. EPSS is 0.73%. Act only if a listed version of A flaw was found is installed.

Which versions are affected?

Compare what you have installed with redhat/enterprise linux 10.0; redhat/enterprise linux 6.0; redhat/enterprise linux 7.0; redhat/enterprise linux 8.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-415: Double Free. EPSS 0.73%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. 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

  2. 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

  3. 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

Sources

  • CVE.orgVulnerability recordCVE-2026-55653

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-55653

    30-day exploitation probability 0.7%

    first.org
  • NIST NVDVulnerability recordCVE-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

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.