CVE-2026-39835Network attack vector

Unauthenticated SSH server crash via nil callbacks

Published May 22, 2026 · Updated Aug 28, 2026

Denial of service in golang.org/x/crypto/ssh before 0.52.0 allows remote attackers to crash SSH servers with a crafted certificate. CertChecker.Authenticate and CheckHostKey invoke an unset authority callback while processing the client-supplied certificate, causing a nil function call and panic. Exposure requires the non-default CertChecker callback configuration; exploitation is unauthenticated and interrupts only the affected SSH server process.

CVSS severity7.5
High
EPSS probability0.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in golang.org/x/crypto/ssh before 0.52.0 allows remote attackers to crash SSH servers with a crafted certificate. CertChecker.Authenticate and CheckHostKey invoke an unset authority callback while processing the client-supplied certificate, causing a nil function call and panic. Exposure requires the non-default CertChecker callback configuration; exploitation is unauthenticated and interrupts only the affected SSH server process.

The record

CVE
CVE-2026-39835
Published
May 22, 2026
Updated
Aug 28, 2026
Vendor
389 Directory Server
Product
Assisted Installer for OpenShift Container Platform
Classifications
CWE-476, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 28, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

389 Directory Server · Assisted Installer for OpenShift Container PlatformAffected versions are unavailable in this record.
389 Directory Server · Red Hat QuayAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift ServerlessAffected versions are unavailable in this record.
389 Directory Server · cert-manager Operator for Red Hat OpenShiftAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift AIAffected versions are unavailable in this record.
389 Directory Server · OpenShift API for Data ProtectionAffected versions are unavailable in this record.
389 Directory Server · Red Hat Edge ManagerAffected versions are unavailable in this record.
389 Directory Server · multicluster engine for Kubernetes 2.17Affected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Dev SpacesAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift for Windows ContainersAffected versions are unavailable in this record.
389 Directory Server · Security Profiles OperatorAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Data FoundationAffected versions are unavailable in this record.
389 Directory Server · multicluster engine for Kubernetes 2.6Affected versions are unavailable in this record.
389 Directory Server · Red Hat Advanced Cluster Security for Kubernetes 4.11Affected versions are unavailable in this record.
389 Directory Server · Red Hat Advanced Cluster Management for KubernetesAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift BuildsAffected versions are unavailable in this record.
389 Directory Server · Red Hat Advanced Cluster Security for KubernetesAffected versions are unavailable in this record.
389 Directory Server · ExternalDNS OperatorAffected versions are unavailable in this record.
389 Directory Server · multicluster engine for Kubernetes 2.10Affected versions are unavailable in this record.
389 Directory Server · External Secrets Operator for Red Hat OpenShiftAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 10Affected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift VirtualizationAffected versions are unavailable in this record.
389 Directory Server · Red Hat Ceph Storage 9Affected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Container Platform 4.22Affected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift GitOpsAffected versions are unavailable in this record.
389 Directory Server · Confidential Compute Attestation OperatorAffected versions are unavailable in this record.
389 Directory Server · multicluster engine for Kubernetes 2.8Affected versions are unavailable in this record.
389 Directory Server · Zero Trust Workload Identity ManagerAffected versions are unavailable in this record.
golang.org/x/crypto · golang.org/x/crypto/sshversion=0 <0.52.0
389 Directory Server · Red Hat build of CryostatAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 9Affected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift PipelinesAffected versions are unavailable in this record.
389 Directory Server · multicluster engine for KubernetesAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Container Platform 4Affected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Dev Workspaces OperatorAffected versions are unavailable in this record.
389 Directory Server · Red Hat Trusted Artifact SignerAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8Affected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Service on AWSAffected versions are unavailable in this record.
389 Directory Server · Logging Subsystem for Red Hat OpenShiftAffected versions are unavailable in this record.

Published CVSS scores

7.5Go ProjectCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5Red HatCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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