CVE-2026-111943Medium· 6.8▾ TwilightPoC available

crypto/x509: golang: crypto/x509: Man-in-the-middle attacks via untrusted intermediate certificates (CVE-2026-111943)

▾ Twilight zone — High severity, or a signal on a lesser flaw

Depth score49/ 100 · Moderate

impact 37.4 · likelihood 0.1 · exploitation 12

⚡ Agent-ready:Raw markdown ↗JSON ↗

Proof of concept

A public proof-of-concept already exists for this vulnerability — see Exploit availability below.

…

Published

Oct 20, 2026

Updated

Oct 26, 2026

CVSS

6.8

Vendor

Red Hat

Product

Red Hat Enterprise Linux AppStream (v. 8)

CWE

CWE-295, CWE-299

Depth score

49 · Moderate

EPSS

0.30% · p22

Platforms

—

Source

CSAF

Vector

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

Exploit availability

Public exploit / PoC code seen in 1 source. Availability, not in-the-wild use.

checked 2026-10-27

GitHub PoCs

5 public repositories

EPSS history

Exploit-prediction probability, daily snapshots since Oct 22.

0.1% → 0.3%▲ 0.2%

Timeline

Disclosure to exploitation, from the record and what we observed since indexing it.

7 events · 6 days

Oct 20, 2026Published
Disclosed via CSAF
Oct 21, 2026CVSS changed
— → 6.8
Oct 21, 2026Severity changed
none → medium
Oct 22, 2026EPSS first tracked
0.1%
Oct 22, 2026Public exploit observed
5 GitHub repos
Oct 26, 2026Record revised
Last analysed / modified upstream
Oct 26, 2026EPSS peak
0.1% → 0.3%

Red Hat CWE-295 CWE-299 #csaf #vex #red-hat #exploit-available #osv #rust #go #cve.org

Affected

Patched in

enterprise_linux_appstream_eus_v_10_0
enterprise_linux_appstream_v_10
enterprise_linux_appstream_v_8
enterprise_linux_appstream_aus_v_8_6
enterprise_linux_appstream_eus_extension_v_8_6
enterprise_linux_appstream_e4s_v_8_8
enterprise_linux_appstream_tus_v_8_8
enterprise_linux_appstream_e4s_v_9_2
enterprise_linux_appstream_e4s_v_9_4
enterprise_linux_appstream_eus_v_9_6
enterprise_linux_appstream_v_9
enterprise_linux_codeready_linux_builder_v_10
enterprise_linux_codeready_linux_builder_v_9
hardened_images
openshift_builds 1.8.3
openshift_builds 1.9.2
openshift_distributed_tracing 3.11

Full technical detail▾

Overview

A flaw was found in Go's crypto/x509 package. The certificate verification process fails to block trust in intermediate certificates associated with a compromised Certificate Authority (CA). A remote attacker presenting a certificate signed by these intermediate authorities can impersonate legitimate servers during secure connections. This flaw can enable an attacker to conduct a man-in-the-middle (MitM) attack to intercept or alter confidential communications.

Vendor advisories

RHSA-2026:89884 · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v. 10.0) · released 2026-10-26 · advisory
RHSA-2026:87040 · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v. 10.0) · released 2026-10-21 · advisory
RHSA-2026:88397 · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v. 10.0) · released 2026-10-22 · advisory
RHSA-2026:88317 · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v. 10.0) · released 2026-10-22 · advisory
RHSA-2026:89892 · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v. 10.0) · released 2026-10-26 · advisory
RHSA-2026:88262 · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10) · released 2026-10-22 · advisory
RHSA-2026:86093 · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10) · released 2026-10-20 · advisory
RHSA-2026:89751 · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10) · released 2026-10-26 · advisory
RHSA-2026:88316 · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10) · released 2026-10-22 · advisory
RHSA-2026:88280 · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10) · released 2026-10-22 · advisory
RHSA-2026:89752 · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10) · released 2026-10-26 · advisory
Red Hat VEX · Important · affected: Ansible Automation Orchestrator 2026, OpenShift Developer Tools and Services, OpenShift Pipelines, OpenShift Serverless, OpenShift Service Mesh 3, Red Hat Ansible Automation Platform 2, … · no fix planned: Red Hat Hardened Images, Ansible Automation Orchestrator 2026, OpenShift Developer Tools and Services, OpenShift Pipelines, … · updated 2026-10-26 · vex
RHSA-2026:88336 · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) · released 2026-10-22 · advisory
RHSA-2026:86203 · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8) · released 2026-10-20 · advisory
RHSA-2026:88188 · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8) · released 2026-10-22 · advisory
RHSA-2026:88189 · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8) · released 2026-10-22 · advisory
RHSA-2026:86196 · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9) · released 2026-10-20 · advisory
RHSA-2026:85899 · Red Hat · fixed in: Red Hat Hardened Images · released 2026-10-20 · advisory
RHSA-2026:86029 · Red Hat · fixed in: Red Hat Hardened Images · released 2026-10-20 · advisory

crypto/x509: golang: crypto/x509: Man-in-the-middle attacks via untrusted intermediate certificates — rated Important by Red Hat. Released 2026-10-20, updated 2026-10-26.

Affected:

Ansible Automation Orchestrator 2026
OpenShift Developer Tools and Services
OpenShift Pipelines
OpenShift Serverless
OpenShift Service Mesh 3
Red Hat Ansible Automation Platform 2
Red Hat Build of Podman Desktop
Red Hat Ceph Storage 7
Red Hat Ceph Storage 8
Red Hat Ceph Storage 9
Red Hat Certification Program for Red Hat Enterprise Linux 9
Red Hat Edge Manager 1
Red Hat Enterprise Linux 10
Red Hat Enterprise Linux 7
Red Hat Enterprise Linux 8
Red Hat Enterprise Linux 9
Red Hat Enterprise Linux AI (RHEL AI) 3
Red Hat Hardened Images
Red Hat OpenShift Container Platform 4
Red Hat OpenShift on AWS
Red Hat OpenShift Virtualization 4
Red Hat OpenStack Platform 16.2
Red Hat OpenStack Platform 17.1
Red Hat OpenStack Platform 18.0
Red Hat Satellite 6
Red Hat Service Interconnect 1
Red Hat Service Interconnect 2
Self-service automation portal 2
Service Telemetry Framework 1.5
streams for Apache Kafka 2
streams for Apache Kafka 3

Fixed:

Red Hat Enterprise Linux AppStream EUS (v. 10.0)
Red Hat Enterprise Linux AppStream (v. 10)
Red Hat Enterprise Linux AppStream (v. 8)
Red Hat Enterprise Linux AppStream AUS (v.8.6)
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6)
Red Hat Enterprise Linux AppStream E4S (v.8.8)
Red Hat Enterprise Linux AppStream TUS (v.8.8)
Red Hat Enterprise Linux AppStream E4S (v.9.2)
Red Hat Enterprise Linux AppStream E4S (v.9.4)
Red Hat Enterprise Linux AppStream EUS (v.9.6)
Red Hat Enterprise Linux AppStream (v. 9)
Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)
Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)
Red Hat Hardened Images
Red Hat OpenShift Builds 1.8.3
Red Hat OpenShift Builds 1.9.2
Red Hat OpenShift distributed tracing 3.11

No fix planned:

Red Hat Hardened Images
Ansible Automation Orchestrator 2026
OpenShift Developer Tools and Services
OpenShift Pipelines
OpenShift Serverless
OpenShift Service Mesh 3
Red Hat Ansible Automation Platform 2
Red Hat Build of Podman Desktop
Red Hat Ceph Storage 7
Red Hat Ceph Storage 8
Red Hat Ceph Storage 9
Red Hat Certification Program for Red Hat Enterprise Linux 9
Red Hat Edge Manager 1
Red Hat Enterprise Linux 10
Red Hat Enterprise Linux 7
Red Hat Enterprise Linux 8
Red Hat Enterprise Linux 9
Red Hat Enterprise Linux AI (RHEL AI) 3
Red Hat OpenShift Container Platform 4
Red Hat OpenShift on AWS
Red Hat OpenShift Virtualization 4
Red Hat OpenStack Platform 16.2
Red Hat OpenStack Platform 17.1
Red Hat OpenStack Platform 18.0
Red Hat Satellite 6
Red Hat Service Interconnect 1
Red Hat Service Interconnect 2
Self-service automation portal 2
Service Telemetry Framework 1.5
streams for Apache Kafka 2
streams for Apache Kafka 3

Not affected:

Red Hat Enterprise Linux AppStream (v. 10)
Red Hat OpenShift Builds 1.8.3
Red Hat OpenShift Builds 1.9.2
Red Hat OpenShift distributed tracing 3.11
Red Hat Ansible Automation Platform 2
Red Hat Enterprise Linux 10
Red Hat Enterprise Linux 7
Red Hat Enterprise Linux 8
Red Hat Enterprise Linux 9
Red Hat Hardened Images

Remediation

For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258 https://access.redhat.com/errata/RHSA-2026:89884 For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258 https://access.redhat.com/errata/RHSA-2026:87040 For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258 https://access.redhat.com/errata/RHSA-2026:88397

Workarounds / mitigations:

See the security bulletin for a detailed mitigation procedure.

Package advisory (CVE-2026-111943)

Affected packages:

webpki-roots >= 0.26.12-0, < 1.0.10

Patched in:

webpki-roots 1.0.10

Source: https://osv.dev/vulnerability/RUSTSEC-2026-0381

References

Change history

Field changes observed since this record was first indexed.

Oct 22, 2026Public exploit / PoC published
Oct 21, 2026CVSS — → 6.8
Oct 21, 2026Severity none → medium

Related vulnerabilities

Connected by shared product, vendor, weakness, or advisory.

#csaf#vex#red-hat#exploit-available#osv#rust#go#cve.org

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