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Vulnerabilities/CVE-2026-55653Public Intelligence Dossier
Source: openbsd · Limited verification•Last verified: •Collection Running
CVE-2026-55653Unknown / EvaluatingMEDIUM (raw)CVSS 6.5CWE-415

A flaw was found in OpenSSH

Published: 23 Jun 2026•Last updated: 15 Oct 2026, 01:47 AM IST•Source identifier: secalert@redhat.com
Dossier completeness: source-provided sections 2 / 3 · rule guidance available. Missing source facts count as incomplete.
Official source
CISA KEV catalog
Unknown
KEV status was not determined.
CVSS score
6.5MEDIUM (raw)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Metric sourcenvd@nist.gov
EPSS probability
0.7%0.007
Percentile53rd
Weakness type
CWE-415
No further CWE recorded
Remediation
Patch status unknown
No fixed version or KB recorded

Why It Matters

Analysis dossier

Why It Matters

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).

SOC priority

Medium

Actively exploited

Unknown

Publicly disclosed

Unknown

Risk basis: Microsoft or Microsoft-managed product relevance; No confirmed exploitation signal in current enrichment

Affected Products & Remediation

4 source-backed products
Affected products and versions (source)
  • openbsd openssh · version range not provided by source · NVD CPE · Source
  • redhat hardened images · version range not provided by source · NVD CPE · Source
  • redhat openshift container platform · 4.0 · NVD CPE · Source
  • redhat enterprise linux · 6.0; 7.0; 8.0; 9.0; 10.0 · NVD CPE · Source
Recorded patch / KBNot provided by source

Vendor or catalog guidance (source)

Not provided by source

Known exploitation (source facts)

Only what a source states. Unknown means no source has said either way; it is not "not exploited".

CISA KEV
Unknown
Exploited (source statement)
Unknown
Publicly disclosed (source)
Unknown

Suggested hunting (rule-based inference)

SecOps Signal recommendation (rule-based inference). These steps are hunting hypotheses from the vulnerability class; they do not state or imply that exploitation occurred here or anywhere.

Matched user-interaction-client (CVSS AV:N, CVSS UI:R)

Exposure

  1. Identify endpoints reporting this CVE, especially those used for email and web browsing.Telemetry: DeviceTvmSoftwareVulnerabilities · A network vector that needs user interaction points at user-facing client software. · Rule user-interaction-client

Exploitation evidence

  1. Review unusual child processes started by the affected client application on affected endpoints.Telemetry: DeviceProcessEvents · Hunting hypothesis from the CVSS vector; it does not show that exploitation occurred. · Rule user-interaction-client

Response

  1. Confirm the source-stated update on affected endpoints.Telemetry: DeviceTvmSoftwareVulnerabilities · A follow-up inventory check verifies remediation. · Rule user-interaction-client

CISA KEV Record

CISA KEV status was not determined for this record.

Change History & Source Data

— No recorded material change

CNA / source
secalert@redhat.com
Record status · verification
UPDATED · NVD API
CPE
cpe:2.3:a:openbsd:openssh:-:*:*:*:*:*:*:*, cpe:2.3:a:redhat:hardened_images:-:*:*:*:*:*:*:*, cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:*, cpe:2.3:o:redhat:enterprise_linux:6.0:*:*:*:*:*:*:*, cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*, cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*, cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*, cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:*

Evidence & Provenance

3 public sources
access.redhat.comSource recordnvd.nist.govSource recordaccess.redhat.comSource record

Linked by the query's stored exact CVE association. Review required tables and validation status before use.

Detection Hunting Query
Target: DeviceTvmSoftwareVulnerabilities•Defender XDR
Detect endpoints exposed to CVE-2026-55653
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2026-55653
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2026-55653"| project DeviceId, DeviceName, OSPlatform, OSVersion, SoftwareVendor, SoftwareName, SoftwareVersion, CveId, VulnerabilitySeverityLevel, RecommendedSecurityUpdate, RecommendedSecurityUpdateId| sort by VulnerabilitySeverityLevel desc
Schema Checked · Not runtime validatedSource: SecOps Signal deterministic template · Limited verificationStatic screening: Passed structure and schema checks; tenant execution is not verified.
Open KQL Library

Correlated briefings

— No published briefing references this CVE

SecOps Signal surfaces public advisory facts only. A missing value means the source has not published it, not that your environment is unaffected. No tenant inventory is connected.