# CVE-2026-42012: Gnutls: gnutls: certificate validation bypass due to improper handling of uri and srv sans

Status: published. Published: 2026-05-26. Updated: 2026-11-03.

A flaw was found in gnutls. A remote attacker could exploit this vulnerability by presenting a specially crafted certificate that contains Uniform Resource Identifier (URI) or Service (SRV) Subject Alternative Names (SANs). This could cause the certificate validation process to incorrectly fall back to checking DNS hostnames against the Common Name (CN), potentially allowing the attacker to spoof legitimate services or intercept sensitive information.

## Remediation

- workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. (source: CNA: redhat)

## Affected products and versions

-  /  (gnutls): 0 (affected). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10 (gnutls): ≥ 0:3.8.10-4.el10_2; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10.0 Extended Update Support (gnutls): ≥ 0:3.8.9-9.el10_0.19; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 Extended Lifecycle Support  - EXTENSION (gnutls): ≥ 0:2.12.23-22.el6_10.1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 Extended Lifecycle Support (gnutls): ≥ 0:3.3.29-9.el7_9.2; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (gnutls): ≥ 0:3.6.16-8.el8_10.6; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support (gnutls): ≥ 0:3.6.14-10.el8_4.1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support (libtasn1): ≥ 0:4.13-3.el8_4.1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On (gnutls): ≥ 0:3.6.14-10.el8_4.1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On (libtasn1): ≥ 0:4.13-3.el8_4.1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support (gnutls): ≥ 0:3.6.16-5.el8_6.5; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support (libtasn1): ≥ 0:4.13-3.el8_6.2; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On (gnutls): ≥ 0:3.6.16-5.el8_6.5; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On (libtasn1): ≥ 0:4.13-3.el8_6.2; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.8 Telecommunications Update Service (gnutls): ≥ 0:3.6.16-7.el8_8.4; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.8 Telecommunications Update Service (libtasn1): ≥ 0:4.13-4.el8_8.1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions (gnutls): ≥ 0:3.6.16-7.el8_8.4; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions (libtasn1): ≥ 0:4.13-4.el8_8.1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (gnutls): ≥ 0:3.8.10-4.el9_8; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions (gnutls): ≥ 0:3.7.6-21.el9_2.7; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions (gnutls): ≥ 0:3.8.3-4.el9_4.6; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9.6 Extended Update Support (gnutls): ≥ 0:3.8.3-6.el9_6.4; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4.20 (openshift/ose-rhel-coreos-9): ≥ 4.20.9.6.202610242033-0; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4.21 (openshift/ose-rhel-coreos-9): ≥ 4.21.9.6.202610241345-0; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4.22 (openshift/ose-rhel-coreos-9): ≥ 4.22.9.8.202610241758-0; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Cert Manager support for Red Hat OpenShift release 1.17 (cert-manager/jetstack-cert-manager-acmesolver-rhel9): ≥ 1791371080; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Cert Manager support for Red Hat OpenShift release 1.17 (cert-manager/jetstack-cert-manager-rhel9): ≥ 1791371069; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Cert Manager support for Red Hat OpenShift release 1.17 (cert-manager/cert-manager-operator-rhel9): ≥ 1791788287; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Cert Manager support for Red Hat OpenShift release 1.17 (cert-manager/cert-manager-operator-bundle): ≥ 1791970484; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Cert Manager support for Red Hat OpenShift release 1.18 (cert-manager/jetstack-cert-manager-acmesolver-rhel9): ≥ 1791459707; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Cert Manager support for Red Hat OpenShift release 1.18 (cert-manager/jetstack-cert-manager-rhel9): ≥ 1791459711; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Cert Manager support for Red Hat OpenShift release 1.18 (cert-manager/cert-manager-istio-csr-rhel9): ≥ 1791459759; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Cert Manager support for Red Hat OpenShift release 1.18 (cert-manager/cert-manager-operator-rhel9): ≥ 1789029076; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Cert Manager support for Red Hat OpenShift release 1.18 (cert-manager/cert-manager-operator-bundle): ≥ 1791966259; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Cert Manager support for Red Hat OpenShift release 1.20 (cert-manager/cert-manager-trust-manager-rhel9): ≥ 1790598593; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Discovery 2 (discovery/discovery-server-rhel9): ≥ 1782159791; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Discovery 2 (discovery/discovery-ui-rhel9): ≥ 1782166952; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Hardened Images (gnutls-main): ≥ 3.8.13-1.hum1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat OpenShift AI 3.4 (rhai/base-image-neuron-rhel9): ≥ 1790703542; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Update Infrastructure 5 (rhui5/cds-rhel9): ≥ 1781525684; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Update Infrastructure 5 (rhui5/haproxy-rhel9): ≥ 1781525671; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Update Infrastructure 5 (rhui5/installer-rhel9): ≥ 1781525693; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Update Infrastructure 5 (rhui5/rhua-rhel9): ≥ 1781525739; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Update Infrastructure 5 (rhui5/cds-kubernetes-tp-rhel9): ≥ 1787241211; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Update Infrastructure 5 (rhui5/installer-tp-rhel9): ≥ 1787135742; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Update Infrastructure 5 (rhui5/rhua-tp-rhel9): ≥ 1787241260; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4 (openshift4/ose-hypershift-rhel9): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4 (openshift/ose-rhel-coreos-8): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 5 (openshift/ose-rhel-coreos-9): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 7.1 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:H/A:N; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: 0.35% as of 2026-11-02; percentile 29.06%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-295

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://access.redhat.com/errata/RHSA-2026:13274 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:20611 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:20612 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:20613 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26319 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26409 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:29197 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:30004 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:30849 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:30850 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:32962 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:33125 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:41921 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:43575 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:58981 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:72502 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:74674 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:82304 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:82322 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:82347 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:82354 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:82372 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:82857 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:82888 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:89197 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:89232 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:89333 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:94442 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2026-42012 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2467441 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://www.gnutls.org/security-new.html#GNUTLS-SA-2026-04-29-7 (CNA: redhat)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-42012; retrieved 2026-11-03; source updated 2026-11-03

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-42012; retrieved 2026-11-03; source updated Not reported

Revision: 247342342381c97ab2abd13b9117171d227bf44262178c1012b5068d3563ac26

Canonical: https://y2.dev/cve/CVE-2026-42012

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