CVE-2026-42012: Improper Certificate Validation in Red Hat Red Hat Enterprise Linux 10
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.
AI Analysis
Technical Summary
The vulnerability CVE-2026-42012 affects the GnuTLS library in Red Hat Enterprise Linux 10. It arises from improper validation of certificates containing URI or SRV Subject Alternative Names (SANs). When such certificates are presented, the validation process may incorrectly fallback to verifying DNS hostnames against the Common Name (CN), which can be exploited by remote attackers to spoof services or intercept sensitive data. Red Hat has released updated RPM packages for Hardened Images including gnutls-3.8.13-1.hum1 to address this issue. However, the vendor advisory does not explicitly confirm the patch status for Red Hat Enterprise Linux 10 itself, and no affected versions are clearly stated. The CVSS v3.1 score is 7.1, indicating a high severity with network attack vector, low attack complexity, no privileges required, user interaction required, unchanged scope, low confidentiality impact, high integrity impact, and no availability impact.
Potential Impact
This vulnerability allows a remote attacker to bypass proper certificate validation by exploiting the fallback mechanism to the Common Name when URI or SRV SANs are present. This can lead to spoofing of legitimate services or interception of sensitive information, compromising the integrity and confidentiality of communications relying on GnuTLS for TLS/SSL. The CVSS score of 7.1 reflects a high severity impact primarily on integrity and confidentiality.
Mitigation Recommendations
Red Hat has released updated Hardened Images RPMs including gnutls-3.8.13-1.hum1 that address this vulnerability. Users of Red Hat Hardened Images should apply these updates as per the vendor instructions at https://images.redhat.com/. For Red Hat Enterprise Linux 10, the vendor advisory does not explicitly confirm patch availability or remediation level; therefore, users should monitor the official Red Hat advisory at https://access.redhat.com/security/cve/CVE-2026-42012 for updates and apply any forthcoming patches promptly. No temporary or workaround fixes are documented. Until patched, caution is advised when trusting certificates with URI or SRV SANs.
CVE-2026-42012: Improper Certificate Validation in Red Hat Red Hat Enterprise Linux 10
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.
CVSS v3.1
Score 7.1high
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability CVE-2026-42012 affects the GnuTLS library in Red Hat Enterprise Linux 10. It arises from improper validation of certificates containing URI or SRV Subject Alternative Names (SANs). When such certificates are presented, the validation process may incorrectly fallback to verifying DNS hostnames against the Common Name (CN), which can be exploited by remote attackers to spoof services or intercept sensitive data. Red Hat has released updated RPM packages for Hardened Images including gnutls-3.8.13-1.hum1 to address this issue. However, the vendor advisory does not explicitly confirm the patch status for Red Hat Enterprise Linux 10 itself, and no affected versions are clearly stated. The CVSS v3.1 score is 7.1, indicating a high severity with network attack vector, low attack complexity, no privileges required, user interaction required, unchanged scope, low confidentiality impact, high integrity impact, and no availability impact.
Potential Impact
This vulnerability allows a remote attacker to bypass proper certificate validation by exploiting the fallback mechanism to the Common Name when URI or SRV SANs are present. This can lead to spoofing of legitimate services or interception of sensitive information, compromising the integrity and confidentiality of communications relying on GnuTLS for TLS/SSL. The CVSS score of 7.1 reflects a high severity impact primarily on integrity and confidentiality.
Mitigation Recommendations
Red Hat has released updated Hardened Images RPMs including gnutls-3.8.13-1.hum1 that address this vulnerability. Users of Red Hat Hardened Images should apply these updates as per the vendor instructions at https://images.redhat.com/. For Red Hat Enterprise Linux 10, the vendor advisory does not explicitly confirm patch availability or remediation level; therefore, users should monitor the official Red Hat advisory at https://access.redhat.com/security/cve/CVE-2026-42012 for updates and apply any forthcoming patches promptly. No temporary or workaround fixes are documented. Until patched, caution is advised when trusting certificates with URI or SRV SANs.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- redhat
- Date Reserved
- 2026-04-23T11:23:46.517Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
- Vendor Advisory Urls
- [{"url":"https://access.redhat.com/security/cve/CVE-2026-42012","vendor":"Red Hat"}]
Threat ID: 6a161534e29bf47b506c521c
Added to database: 05/26/2026, 21:48:36 UTC
Last enriched: 07/21/2026, 18:22:57 UTC
Last updated: 07/25/2026, 22:23:54 UTC
Views: 186
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