CVE-2026-27137Network attack vectorHinoki check available

Certificate identity bypass via overwritten email constraint

Published Mar 6, 2026 · Updated Sep 14, 2026

Improper certificate validation in Go crypto/x509 1.26.0 allows attackers to accept disallowed email identities via crafted chains. Certificate.Verify stores full-email constraints in a map keyed only by the case-sensitive local portion, so a later constraint with the same local portion overwrites an earlier domain. Exploitation requires a trusted CA to issue a chain containing a prohibited or excluded email address, after which verification can accept that identity.

CVSS severity7.5
High
EPSS probability0.61%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
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Summary

What happened

Improper certificate validation in Go crypto/x509 1.26.0 allows attackers to accept disallowed email identities via crafted chains. Certificate.Verify stores full-email constraints in a map keyed only by the case-sensitive local portion, so a later constraint with the same local portion overwrites an earlier domain. Exploitation requires a trusted CA to issue a chain containing a prohibited or excluded email address, after which verification can accept that identity.

The record

CVE
CVE-2026-27137
Published
Mar 6, 2026
Updated
Sep 14, 2026
Vendor
Red Hat
Product
Red Hat Lightspeed for Runtimes
Classifications
CWE-295
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 6, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 14, 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?

Red Hat · Red Hat Lightspeed for RuntimesAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 10Affected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux AIAffected versions are unavailable in this record.
Red Hat · Red Hat Trusted Artifact SignerAffected versions are unavailable in this record.
Red Hat · Red Hat OpenStack PlatformAffected versions are unavailable in this record.
Red Hat · Red Hat 3scale API ManagementAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 8Affected versions are unavailable in this record.
Red Hat · Red Hat OpenShift Developer Tools and ServicesAffected versions are unavailable in this record.
Red Hat · ExternalDNS OperatorAffected versions are unavailable in this record.
Red Hat · GatekeeperAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 10.0 Extended Update SupportAffected versions are unavailable in this record.
Red Hat · Red Hat Developer HubAffected versions are unavailable in this record.
Go standard library · crypto/x509version=1.26.0-0 <1.26.1
Red Hat · Deployment Validation OperatorAffected versions are unavailable in this record.
Red Hat · Red Hat Connectivity LinkAffected versions are unavailable in this record.
Red Hat · Red Hat OpenShift LightspeedAffected versions are unavailable in this record.
Red Hat · Red Hat QuayAffected versions are unavailable in this record.
Red Hat · Red Hat Migration Toolkit for ContainersAffected versions are unavailable in this record.
Red Hat · DevWorkspace OperatorAffected versions are unavailable in this record.
Red Hat · Red Hat OpenShift distributed tracing 3Affected versions are unavailable in this record.
Red Hat · Multicluster Global HubAffected versions are unavailable in this record.
Red Hat · Zero Trust Workload Identity ManagerAffected versions are unavailable in this record.
Red Hat · Red Hat Edge ManagerAffected versions are unavailable in this record.
Red Hat · Red Hat OpenShift Service on AWSAffected versions are unavailable in this record.
Red Hat · Red Hat Ansible Automation PlatformAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 9Affected versions are unavailable in this record.
Red Hat · Red Hat OpenShift Data FoundationAffected versions are unavailable in this record.
Red Hat · Red Hat OpenShift Dev SpacesAffected versions are unavailable in this record.
Red Hat · Red Hat OpenStack Services on OpenShiftAffected versions are unavailable in this record.
Red Hat · Red Hat OpenShift AIAffected versions are unavailable in this record.
Red Hat · Red Hat OpenStack Platform 16.2Affected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 9.4 Update Services for SAP SolutionsAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 9.2 Update Services for SAP SolutionsAffected versions are unavailable in this record.
Red Hat · Red Hat build of Apache Camel - HawtIO 4Affected versions are unavailable in this record.
Red Hat · Red Hat multicluster global hubAffected versions are unavailable in this record.
Red Hat · Logical Volume Manager StorageAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 9.6 Extended Update SupportAffected versions are unavailable in this record.
Red Hat · Red Hat OpenShift ServerlessAffected versions are unavailable in this record.
Red Hat · Logging for Red Hat OpenShiftAffected versions are unavailable in this record.
Red Hat · Red Hat Hardened ImagesAffected versions are unavailable in this record.
Red Hat · Red Hat build of TrusteeAffected versions are unavailable in this record.
Red Hat · OpenShift Cluster Manager CLIAffected versions are unavailable in this record.
Red Hat · Red Hat Streams for Apache KafkaAffected versions are unavailable in this record.
Red Hat · Red Hat Certification Program for Red Hat Enterprise Linux 9Affected versions are unavailable in this record.
Red Hat · Red Hat SatelliteAffected versions are unavailable in this record.
Red Hat · Red Hat OpenShift Container PlatformAffected versions are unavailable in this record.
Red Hat · Fence Agents Remediation OperatorAffected versions are unavailable in this record.
Red Hat · Assisted Installer for Red Hat OpenShift Container PlatformAffected versions are unavailable in this record.
Red Hat · Red Hat Web TerminalAffected versions are unavailable in this record.
Red Hat · Red Hat Advanced Cluster Management for KubernetesAffected versions are unavailable in this record.
Red Hat · Builds for Red Hat OpenShiftAffected versions are unavailable in this record.
Red Hat · Red Hat OpenShift GitOpsAffected versions are unavailable in this record.
Red Hat · Red Hat OpenShift API for Data ProtectionAffected versions are unavailable in this record.
Red Hat · Mirror Registry for Red Hat OpenShiftAffected versions are unavailable in this record.
Red Hat · Red Hat OpenShift PipelinesAffected versions are unavailable in this record.

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5Red Hat Security Data ProviderCVSS: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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-295Improper Certificate Validation

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

See the directory against your own environment.

Your stack

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