🛡️ CVE-2026-55653 — enterprise-linux

🟡 CVSS 4.3 — Medium ⚠️ Exploit Public CWE-415 NVD
4.3
CVSS Score
0 Low4 Medium7 High9 Critical10

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).

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. A user must be tricked into taking some action. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability low.

Weakness class

CVE-2026-55653 is classified as CWE-415: Double Free. The same allocation is released twice, corrupting allocator bookkeeping.

Affected software

CVE-2026-55653 is recorded against 4 packages.

  • enterprise-linux
  • hardened-images
  • openshift-container-platform
  • openssh

Timeline and source

Published on 23 June 2026 and last revised on 30 July 2026. A public exploit is known to exist, which raises the urgency of patching considerably. Record sourced from NVD.

References

access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
access.redhat.com
bugzilla.redhat.com

Details

Severity MEDIUM
CVSS Score 4.3
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
CWE CWE-415
Public Exploit ⚠️ Yes
Source NVD
Published 2026-06-23
Updated 2026-08-11
Modified 2026-07-30
Fix URL N/A

Affected Packages

Software From version Fixed in
enterprise-linux — —
hardened-images — —
openshift-container-platform — —
openssh — —

Similar Threats

Exploit Protection

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