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CVE-2026-55653

medium

A flaw was found in OpenSSH.

Vendor / product: 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).

CVSS
6.5
6.5 (CVSS v3.1)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Severity source: NVD CVSS v3.1 (nvd@nist.gov)
Timeline (UTC)
Published: 2026-06-23 04:17
Modified: 2026-10-29 23:16
NVD status: Modified
Last synced 6 hours ago
Verified against the source API 2026-10-29 23:32 UTC
Exploitation
Not listed in CISA KEV (as of last catalog sync)
Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).

Affected products

openbsd / openssh all versions
redhat / hardened_images all versions
redhat / openshift_container_platform 4.0
redhat / enterprise_linux 6.0, 7.0, 8.0, 9.0, 10.0

Weakness classification (CWE)

CWE-415

Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.

Mitigation & advisories

Vendor advisory: https://access.redhat.com/security/cve/CVE-2026-55653
Vendor advisory: https://bugzilla.redhat.com/show_bug.cgi?id=2462351

References

Data sources

NVD CVE API 2.0 — fetched 2026-10-29 23:32 UTC · record ↗

Learn the basics

Understanding CVEs and CVSS Scores

Related CVEs

CVE-2026-55655CVE-2026-60002CVE-2026-106583CVE-2026-106585CVE-2023-38408