Invoking Encrypted Client Hello privacy leak in crypto/tls
Priority LOW 30CWE-201Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- Low · None · None
- Fix status
- Partial Red Hat: 7 fixed, 76 without a fix
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and Red Hat. Impact type from CWE-201.
Summary
Handshakes which used Encrypted Client Hello could be de-anonymized by a passive network observer due to a disclosure of pre-shared key identities in the unencrypted client hello.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00382 32nd percentileScored 2026-11-07
Fix Partial crypto/tls (Go standard library): 1.25.12, 1.26.5, 1.27.0-rc.2Red Hat: 9 advisoriesRed Hat: 7 fixed, 76 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Go standard library | crypto/tls | before 1.25.12; 1.26.0-0 to before 1.26.5; 1.27.0-0 to before 1.27.0-rc.2 | 1.25.12, 1.26.5, 1.27.0-rc.2 | Patch available | CNA |
- crypto/tls VendorGo standard library Affected before 1.25.12; 1.26.0-0 to before 1.26.5; 1.27.0-0 to before 1.27.0-rc.2 Fixed in 1.25.12, 1.26.5, 1.27.0-rc.2 Patch available CNA
CPE configurations NVD · 2
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:golang:go:*:*:*:*:*:*:*:* | 1.23.0 to before 1.25.12; 1.26.0 to before 1.26.5 | Vulnerable | Go standard library |
| cpe:2.3:a:golang:go:1.27:rc1:*:*:*:*:*:* | 1.27 rc1 | Vulnerable | Go standard library |
- cpe:2.3:a:golang:go:*:*:*:*:*:*:*:* Versions 1.23.0 to before 1.25.12; 1.26.0 to before 1.26.5 Vulnerable ·Go standard library
- cpe:2.3:a:golang:go:1.27:rc1:*:*:*:*:*:* Versions 1.27 rc1 Vulnerable ·Go standard library
Remediation
- Fix · CNA crypto/tls (Go standard library) Fixed in 1.25.12, 1.26.5, 1.27.0-rc.2
Red Hat 9 advisories
- RHSA-2026:91249 Released 2026-10-27 · Red Hat rating CriticalRed Hat AI Base Images 3.5.5 (Neuron)
- Red Hat OpenShift AI 3.5 registry.redhat.io/rhai/base-image-neuron-rhel9
- RHSA-2026:91248 Released 2026-10-27 · Red Hat rating CriticalRed Hat AI Base Images 3.4.6 (Neuron)
- Red Hat OpenShift AI 3.4 registry.redhat.io/rhai/base-image-neuron-rhel9
- RHSA-2026:66364 Released 2026-09-10 · Red Hat rating Importantgit-lfs security update
- Red Hat Enterprise Linux AppStream (v. 9) git-lfs-3.7.1-4.el9_8.3
Show 6 more Red Hat advisories
- RHSA-2026:54773 Released 2026-08-13 · Red Hat rating ImportantRed Hat build of OpenTelemetry 3.10.2 release
- Red Hat OpenShift distributed tracing 3.10.1 registry.redhat.io/rhosdt/opentelemetry-collector-rhel9, registry.redhat.io/rhosdt/opentelemetry-rhel9-operator
- RHSA-2026:38995 Released 2026-07-13 · Red Hat rating Importantgo-toolset:rhel8 security, bug fix, and enhancement update
- Red Hat Enterprise Linux AppStream (v. 8) delve-1.26.1-1.module+el8.10.0+24516+40554724.aarch64::go-toolset:rhel8, delve-1.26.1-1.module+el8.10.0+24516+40554724.ppc64le::go-toolset:rhel8, delve-1.26.1-1.module+el8.10.0+24516+40554724.src::go-toolset:rhel8 +22
- RHSA-2026:37435 Released 2026-07-09 · Red Hat rating Importantgolang security, bug fix, and enhancement update
- Red Hat Enterprise Linux AppStream (v. 9) go-toolset-1.26.5-1.el9_8, golang-1.26.5-1.el9_8, golang-bin-1.26.5-1.el9_8 +5
- RHSA-2026:37436 Released 2026-07-09 · Red Hat rating Importantgolang security, bug fix, and enhancement update
- Red Hat Enterprise Linux AppStream (v. 10) go-toolset-1.26.5-1.el10_2, golang-1.26.5-1.el10_2, golang-bin-1.26.5-1.el10_2 +5
- RHSA-2026:36510 Released 2026-07-08 · Red Hat rating ImportantRed Hat Hardened Images RPMs bug fix and enhancement update
- Red Hat Hardened Images golang1.25-1.25.12-0.1.hum1@aarch64, golang1.25-1.25.12-0.1.hum1@src, golang1.25-1.25.12-0.1.hum1@x86_64 +10
- RHSA-2026:36477 Released 2026-07-08 · Red Hat rating ImportantRed Hat Hardened Images RPMs bug fix and enhancement update
- Red Hat Hardened Images golang1.26-1.26.5-0.1.hum1@aarch64, golang1.26-1.26.5-0.1.hum1@src, golang1.26-1.26.5-0.1.hum1@x86_64 +10
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Assisted Installer for Red Hat OpenShift Container Platform 2 | Affected | No fix yet: Fix deferred |
| Builds for Red Hat OpenShift | Affected | No fix yet: Fix deferred |
| Compliance Operator | Affected | No fix yet: Fix deferred |
| Confidential Compute Attestation | Affected | No fix yet: Fix deferred |
| Cryostat 4 | Affected | No fix yet: Fix deferred |
| Custom Metric Autoscaler operator for Red Hat Openshift | Affected | No fix yet: Fix deferred |
| Deployment Validation Operator | Affected | No fix yet: Fix deferred |
| External Secrets Operator for Red Hat OpenShift | Affected | No fix yet: Fix deferred |
| Fence Agents Remediation Operator | Affected | No fix yet: Fix deferred |
| File Integrity Operator | Affected | No fix yet: Fix deferred |
| Gatekeeper 3 | Affected | No fix yet: Fix deferred |
| Logging Subsystem for Red Hat OpenShift | Affected | No fix yet: Fix deferred |
| Logical Volume Manager Storage | Affected | No fix yet: Fix deferred |
| Machine Deletion Remediation Operator | Affected | No fix yet: Fix deferred |
| Migration Toolkit for Applications 8 | Affected | No fix yet: Fix deferred |
| Migration Toolkit for Containers | Affected | No fix yet: Fix deferred |
| Multiarch Tuning Operator | Affected | No fix yet: Fix deferred |
| Multicluster Engine for Kubernetes | Affected | No fix yet: Fix deferred |
| Multicluster Global Hub | Affected | No fix yet: Fix deferred |
| Network Observability Operator | Affected | No fix yet: Fix deferred |
| Node HealthCheck Operator | Affected | No fix yet: Fix deferred |
| OpenShift API for Data Protection | Affected | No fix yet: Fix deferred |
| OpenShift Developer Tools and Services | Affected | No fix yet: Fix deferred |
| OpenShift Lightspeed | Affected | No fix yet: Fix deferred |
| OpenShift Pipelines | Affected | No fix yet: Fix deferred |
| OpenShift Serverless | Affected | No fix yet: Fix deferred |
| OpenShift Service Mesh 3 | Affected | No fix yet: Fix deferred |
| OpenShift Source-to-Image (S2I) | Affected | No fix yet: Fix deferred |
| Power monitoring for Red Hat OpenShift | Affected | No fix yet: Fix deferred |
| Red Hat 3scale API Management Platform 2 | Affected | No fix yet: Fix deferred |
| Red Hat Advanced Cluster Management for Kubernetes 2 | Affected | No fix yet: Fix deferred |
| Red Hat Advanced Cluster Security 4 | Affected | No fix yet: Fix deferred |
| Red Hat Ansible Automation Platform 2 | Affected | No fix yet: Fix deferred |
| Red Hat Ceph Storage 5 | Affected | No fix yet: Fix deferred |
| Red Hat Ceph Storage 6 | Affected | No fix yet: Fix deferred |
| Red Hat Ceph Storage 7 | Affected | No fix yet: Fix deferred |
| Red Hat Ceph Storage 8 | Affected | No fix yet: Fix deferred |
| Red Hat Ceph Storage 9 | Affected | No fix yet: Fix deferred |
| Red Hat Connectivity Link 1 | Affected | No fix yet: Fix deferred |
| Red Hat Developer Hub 1 | Affected | No fix yet: Fix deferred |
| Red Hat Edge Manager 1 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 7 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux AI (RHEL AI) 3 | Affected | No fix yet: Fix deferred |
| Red Hat Hardened Images | Affected | No fix yet: Fix deferred |
| Red Hat Lightspeed for Runtimes Operator | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Cluster Manager CLI | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Dev Spaces | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Dev Workspaces Operator | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift GitOps | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Virtualization 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift distributed tracing 3 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift for Windows Containers | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift on AWS | Affected | No fix yet: Fix deferred |
| Red Hat OpenStack Platform 16.2 | Affected | No fix yet: Fix deferred |
| Red Hat OpenStack Platform 17.1 | Affected | No fix yet: Fix deferred |
| Red Hat OpenStack Platform 18.0 | Affected | No fix yet: Fix deferred |
| Red Hat Openshift Data Foundation 4 | Affected | No fix yet: Fix deferred |
| Red Hat Quay 3 | Affected | No fix yet: Fix deferred |
| Red Hat Satellite 6 | Affected | No fix yet: Fix deferred |
| Red Hat Service Interconnect 2 | Affected | No fix yet: Fix deferred |
| Red Hat Trusted Artifact Signer | Affected | No fix yet: Fix deferred |
| Red Hat Web Terminal | Affected | No fix yet: Fix deferred |
| Security Profiles Operator | Affected | No fix yet: Fix deferred |
| Service Telemetry Framework 1.5 | Affected | No fix yet: Fix deferred |
| Zero Trust Workload Identity Manager | Affected | No fix yet: Fix deferred |
| Zero Trust Workload Identity Manager - Tech Preview | Affected | No fix yet: Fix deferred |
| cert-manager Operator for Red Hat OpenShift | Affected | No fix yet: Fix deferred |
| mirror registry for Red Hat OpenShift 2 | Affected | No fix yet: Fix deferred |
| streams for Apache Kafka 2 | Affected | No fix yet: Fix deferred |
| streams for Apache Kafka 3 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux AppStream (v. 10) | Fixed | RHSA-2026:37436 |
| Red Hat Enterprise Linux AppStream (v. 8) | Fixed | RHSA-2026:38995 |
| Red Hat Enterprise Linux AppStream (v. 9) | Fixed | RHSA-2026:37435, RHSA-2026:66364 |
| Red Hat Hardened Images | Fixed | RHSA-2026:36477, RHSA-2026:36510 |
| Red Hat OpenShift AI 3.4 | Fixed | RHSA-2026:91248 |
| Red Hat OpenShift AI 3.5 | Fixed | RHSA-2026:91249 |
| Red Hat OpenShift distributed tracing 3.10.1 | Fixed | RHSA-2026:54773 |
Not affected: 1 product
- Red Hat OpenShift distributed tracing 3.10.1
Timeline
- 2026-10-02 Threatist record created from CVE-2026-42505
- 2026-10-03 Alias added: GHSA-ff52-ph69-cf7x
- 2026-10-16 Affected versions changed · Red Hat
- 2026-10-27 Affected versions changed · Red Hat
- 2026-10-30 Fix available: RHSA-2026:91248 · Red Hat
- 2026-10-30 Fix available: RHSA-2026:91249 · Red Hat
- 2026-10-30 Fix available: Red Hat OpenShift AI 3.4, Red Hat OpenShift AI 3.5 · Red Hat
- 2026-10-30 Affected versions changed · Red Hat
- 2026-10-31 Fix available: Red Hat OpenShift distributed tracing 3.10.1 · Red Hat
References
More Go standard library Go vulnerabilities
- TI-2020-00578 Improper certificate validation in Microsoft Windows KEVCVSS 3.1HIGH 8.1
- TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
- TI-2018-05208 The "go get" implementation in Go 1.9.4, when the -insecure command-line option is used… CVSS 3.1HIGH 8.8
- TI-2018-12083 Improper input validation in [UNKNOWN] golang CVSS 3.1HIGH 8.1
- TI-2024-16306 Mishandling of corrupt central directory record in archive/zip CVSS 3.1MEDIUM 5.5
- TI-2021-15910 Go before 1.16.9 and 1.17.x before 1.17.2 has a Buffer Overflow via large arguments in a… CVSS 3.1CRITICAL 9.8
Sources
- CVE-2026-42505 · CVE Program
- CVE-2026-42505 · NVD
- FIRST EPSS
- GHSA-ff52-ph69-cf7x · GitHub Advisory Database · CC BY 4.0
- CVE-2026-42505 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences