CVE-2026-42012
High
Description
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.
SeverityHigh
CVSS7.1
Exploit probability—
Product
Gnutls
PublishedMay 26, 2026
First seenMay 26, 2026
Weakness typeCWE-295CWE-295
How to fix
Vendor advisories
- access.redhat.com/errata/RHSA-2026:13274
- access.redhat.com/errata/RHSA-2026:20611
- access.redhat.com/errata/RHSA-2026:20612
- access.redhat.com/errata/RHSA-2026:20613
- access.redhat.com/errata/RHSA-2026:26319
- access.redhat.com/errata/RHSA-2026:26409
- access.redhat.com/errata/RHSA-2026:29197
- access.redhat.com/errata/RHSA-2026:30004
- access.redhat.com/errata/RHSA-2026:30849
- access.redhat.com/errata/RHSA-2026:30850
- access.redhat.com/errata/RHSA-2026:32962
- access.redhat.com/errata/RHSA-2026:33125
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| gnutls | 0 | — |
| Red Hat Red Hat Enterprise Linux 10 | No range specified | — |
| Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support | No range specified | — |
| Red Hat Red Hat Enterprise Linux 6 Extended Lifecycle Support - EXTENSION | No range specified | — |
| Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support | No range specified | — |
| enterprise_linux 8 | No range specified | — |
| rhel_aus 8.4 | No range specified | — |
| rhel_aus 8.6 | No range specified | — |
| rhel_e4s 8.8 | No range specified | — |
| enterprise_linux 9 | No range specified | — |
| rhel_e4s 9.2 | No range specified | — |
| rhel_e4s 9.4 | No range specified | — |
| rhel_eus 9.6 | No range specified | — |
| openshift 4.20 | No range specified | — |
| openshift 4.21 | No range specified | — |
| openshift 4.22 | No range specified | — |
| cert_manager 1.17 | No range specified | — |
| cert_manager 1.18 | No range specified | — |
| cert_manager 1.20 | No range specified | — |
| discovery 2 | No range specified | — |
| Red Hat Red Hat Hardened Images | No range specified | — |
| openshift_ai 3.4 | No range specified | — |
| rhui 5 | No range specified | — |
| Red Hat Red Hat OpenShift Container Platform 4 | No range specified | — |
| Red Hat Red Hat OpenShift Container Platform 5 | No range specified | — |
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