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CVE Record

CVE-2026-55653: Openssh: double free in red hat enterprise linux versions of openssh dh-gex client path during fips known-group validation leads to client-side denial of service

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).

MediumCVSS 4.3Not KEV-listedUpdated
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Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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ATT&CK lookup starting points

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description · low confidence lookup

Container behavior lookup

The affected technology mentions containers, so container-specific ATT&CK technique review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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CVE-2026-55653 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
4.3 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
5Timeline events
1ADP providers
41Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
4.3CVSS 3.1MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L2.81.4redhat

Vulnerability scoring details

Base CVSS 3.1 score

4.3Medium
CVSS 3.1 vector shape for CVE-2026-55653Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. Source timelineredhat

    Reported to Red Hat.

  2. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  3. Source timelineredhat

    Made public.

  4. CVE publishedCVE Program

    The CVE record was published.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Red HatRed Hat Enterprise Linux 10openssh, 0:9.9p1-25.el10_2affected
Red HatRed Hat Enterprise Linux 10.0 Extended Update Supportopenssh, 0:9.9p1-7.el10_0.5affected
Red HatRed Hat Enterprise Linux 8openssh, 0:8.0p1-30.el8_10affected
Red HatRed Hat Enterprise Linux 8openssh, 0:8.0p1-30.el8_10affected
Red HatRed Hat Enterprise Linux 9openssh, 0:9.9p1-9.el9_8affected
Red HatRed Hat Enterprise Linux 9openssh, 0:9.9p1-9.el9_8affected
Red HatRed Hat Enterprise Linux 9.4 Update Services for SAP Solutionsopenssh, 0:8.7p1-38.el9_4.10affected
Red HatRed Hat Enterprise Linux 9.6 Extended Update Supportopenssh, 0:8.7p1-45.el9_6.5affected
Red HatRed Hat Hardened Imagesopenssh-main, 10.3p1-6.hum1affected
Red HatRed Hat OpenShift AI 3.0rhai/base-image-cuda-rhel9, 1791818590affected
Red HatRed Hat OpenShift AI 3.0rhai/base-image-cpu-rhel9, 1791818589affected
Red HatRed Hat OpenShift AI 3.0rhai/base-image-spyre-rhel9, 1791818505affected
Red HatRed Hat OpenShift AI 3.0rhai/base-image-tpu-rhel9, 1791818496affected
Red HatRed Hat OpenShift AI 3.0rhai/base-image-rocm-rhel9, 1791818502affected
Red HatRed Hat OpenShift AI 3.2rhai/base-image-spyre-rhel9, 1791818602affected
Red HatRed Hat OpenShift AI 3.2rhai/base-image-cpu-rhel9, 1791818598affected
Red HatRed Hat OpenShift AI 3.2rhai/base-image-tpu-rhel9, 1791818512affected
Red HatRed Hat OpenShift AI 3.2rhai/base-image-cuda-rhel9, 1791818587affected
Red HatRed Hat OpenShift AI 3.2rhai/base-image-rocm-rhel9, 1791818778affected
Red HatRed Hat OpenShift AI 3.2rhai/base-image-rocm-rhel9, 1791818512affected
Red HatRed Hat OpenShift AI 3.3rhai/base-image-tpu-rhel9, 1791818782affected
Red HatRed Hat OpenShift AI 3.3rhai/base-image-rocm-6.4-rhel9, 1791818782affected
Red HatRed Hat OpenShift AI 3.3rhai/base-image-cuda-12.9-rhel9, 1791818627affected
Red HatRed Hat OpenShift AI 3.3rhai/base-image-rocm-7.0-rhel9, 1791818790affected
Red HatRed Hat OpenShift AI 3.3rhai/base-image-cpu-rhel9, 1791818874affected
Red HatRed Hat OpenShift AI 3.3rhai/base-image-neuron-rhel9, 1791818792affected
Red HatRed Hat OpenShift AI 3.3rhai/base-image-cuda-13.0-rhel9, 1791818662affected
Red HatRed Hat OpenShift AI 3.3rhai/base-image-spyre-rhel9, 1791818877affected
Red HatRed Hat OpenShift AI 3.4rhai/base-image-neuron-rhel9, 1791883722affected
Red HatRed Hat OpenShift AI 3.4rhai/base-image-cuda-12.9-rhel9, 1791881612affected
Weakness

CWE details

CWE-415

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

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Double Free

Double Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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