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

Severity: high (CVSS 7.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-26 · updated 2026-10-14
Weakness: CWE-295

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.

Affected products

Red Hat Cert Manager support for Red Hat OpenShift release 1.17: all versions — fixed in 1791371069, 1791371080, 1791788287, 1791970484
Red Hat Cert Manager support for Red Hat OpenShift release 1.18: all versions — fixed in 1789029076, 1791459707, 1791459711, 1791459759, 1791966259
Red Hat Cert Manager support for Red Hat OpenShift release 1.20: all versions — fixed in 1790598593
Red Hat OpenShift Container Platform 4.18: all versions
Red Hat Discovery 2: all versions — fixed in 1782159791, 1782166952
Red Hat Enterprise Linux 10: all versions — fixed in 0:3.8.10-4.el10_2
Red Hat Enterprise Linux 10.0 Extended Update Support: all versions — fixed in 0:3.8.9-9.el10_0.19
Red Hat Enterprise Linux 6: all versions
Red Hat Enterprise Linux 7 Extended Lifecycle Support: all versions — fixed in 0:3.3.29-9.el7_9.2
Red Hat Enterprise Linux 8: all versions — fixed in 0:3.6.16-8.el8_10.6
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support: all versions — fixed in 0:3.6.14-10.el8_4.1, 0:4.13-3.el8_4.1
Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On: all versions — fixed in 0:3.6.14-10.el8_4.1, 0:4.13-3.el8_4.1
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support: all versions — fixed in 0:3.6.16-5.el8_6.5, 0:4.13-3.el8_6.2
Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On: all versions — fixed in 0:3.6.16-5.el8_6.5, 0:4.13-3.el8_6.2
Red Hat Enterprise Linux 8.8 Telecommunications Update Service: all versions — fixed in 0:3.6.16-7.el8_8.4, 0:4.13-4.el8_8.1
Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions: all versions — fixed in 0:3.6.16-7.el8_8.4, 0:4.13-4.el8_8.1
Red Hat Enterprise Linux 9: all versions — fixed in 0:3.8.10-4.el9_8
Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions: all versions — fixed in 0:3.7.6-21.el9_2.7
Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions: all versions — fixed in 0:3.8.3-4.el9_4.6
Red Hat Enterprise Linux 9.6 Extended Update Support: all versions — fixed in 0:3.8.3-6.el9_6.4
Red Hat Hardened Images: all versions — fixed in 3.8.13-1.hum1
Red Hat OpenShift AI 3.4: all versions — fixed in 1790703542
Red Hat Update Infrastructure 5: all versions — fixed in 1781525671, 1781525684, 1781525693, 1781525739, 1787135742, 1787241211

How to fix

Upgrade to a fixed version: Red Hat Cert Manager support for Red Hat OpenShift release 1.17 1791371069, 1791371080, 1791788287, 1791970484; Red Hat Cert Manager support for Red Hat OpenShift release 1.18 1789029076, 1791459707, 1791459711, 1791459759; Red Hat Cert Manager support for Red Hat OpenShift release 1.20 1790598593; Red Hat Discovery 2 1782159791, 1782166952; Red Hat Enterprise Linux 10 0:3.8.10-4.el10_2; Red Hat Enterprise Linux 10.0 Extended Update Support 0:3.8.9-9.el10_0.19; Red Hat Enterprise Linux 7 Extended Lifecycle Support 0:3.3.29-9.el7_9.2; Red Hat Enterprise Linux 8 0:3.6.16-8.el8_10.6; Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support 0:3.6.14-10.el8_4.1, 0:4.13-3.el8_4.1; Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On 0:3.6.14-10.el8_4.1, 0:4.13-3.el8_4.1; Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support 0:3.6.16-5.el8_6.5, 0:4.13-3.el8_6.2; Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On 0:3.6.16-5.el8_6.5, 0:4.13-3.el8_6.2. Check the vendor advisory for mitigations.

References

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