Описание
A flaw was found in gnutls. This vulnerability occurs because gnutls performs case-sensitive comparisons of nameConstraints labels, specifically for dNSName (DNS) or rfc822Name (email) constraints within excludedSubtrees or permittedSubtrees. A remote attacker can exploit this by crafting a leaf certificate with casing differences in the Subject Alternative Name (SAN), leading to a policy bypass where a certificate that should be rejected is instead accepted. This could result in unauthorized access or information disclosure.
Отчет
This issue is particularly important because it affects the correct enforcement of X.509 nameConstraints, which are specifically designed to limit the authority of subordinate CAs. In GnuTLS, the use of case-sensitive comparisons (memcmp) for dNSName and the domain portion of rfc822Name violates the case-insensitive matching requirements defined in RFC 5280 and RFC 4343. As a result, a constrained subordinate CA can bypass excludedSubtrees or permittedSubtrees restrictions simply by changing the letter casing of a domain in the SAN (e.g., ExAmPlE.CoM vs example.com). Since nameConstraints are often the only mechanism enforcing domain boundaries in delegated PKI hierarchies, this flaw effectively allows a malicious or compromised sub-CA to issue certificates for domains that should be cryptographically prohibited, enabling unauthorized certificate validation and potential TLS impersonation of restricted services.
Меры по смягчению последствий
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.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 6 | gnutls | Affected | ||
| Red Hat OpenShift Container Platform 4 | openshift4/ose-hypershift-rhel9 | Under investigation | ||
| Red Hat OpenShift Container Platform 4 | rhcos | Affected | ||
| Red Hat Enterprise Linux 10 | gnutls | Fixed | RHSA-2026:20613 | 26.05.2026 |
| Red Hat Enterprise Linux 10.0 Extended Update Support | gnutls | Fixed | RHSA-2026:26409 | 16.06.2026 |
| Red Hat Enterprise Linux 7 Extended Lifecycle Support | gnutls | Fixed | RHSA-2026:43575 | 22.07.2026 |
| Red Hat Enterprise Linux 8 | gnutls | Fixed | RHSA-2026:20611 | 26.05.2026 |
| Red Hat Enterprise Linux 8 | gnutls | Fixed | RHSA-2026:20611 | 26.05.2026 |
| Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | gnutls | Fixed | RHSA-2026:33125 | 29.06.2026 |
| Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | libtasn1 | Fixed | RHSA-2026:33125 | 29.06.2026 |
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Дополнительная информация
Статус:
EPSS
6.5 Medium
CVSS3
Связанные уязвимости
A flaw was found in gnutls. This vulnerability occurs because gnutls performs case-sensitive comparisons of `nameConstraints` labels, specifically for `dNSName` (DNS) or `rfc822Name` (email) constraints within `excludedSubtrees` or `permittedSubtrees`. A remote attacker can exploit this by crafting a leaf certificate with casing differences in the Subject Alternative Name (SAN), leading to a policy bypass where a certificate that should be rejected is instead accepted. This could result in unauthorized access or information disclosure.
A flaw was found in gnutls. This vulnerability occurs because gnutls performs case-sensitive comparisons of `nameConstraints` labels, specifically for `dNSName` (DNS) or `rfc822Name` (email) constraints within `excludedSubtrees` or `permittedSubtrees`. A remote attacker can exploit this by crafting a leaf certificate with casing differences in the Subject Alternative Name (SAN), leading to a policy bypass where a certificate that should be rejected is instead accepted. This could result in unauthorized access or information disclosure.
Gnutls: gnutls: policy bypass due to case-sensitive nameconstraints comparison
A flaw was found in gnutls. This vulnerability occurs because gnutls p ...
A flaw was found in gnutls. This vulnerability occurs because gnutls performs case-sensitive comparisons of `nameConstraints` labels, specifically for `dNSName` (DNS) or `rfc822Name` (email) constraints within `excludedSubtrees` or `permittedSubtrees`. A remote attacker can exploit this by crafting a leaf certificate with casing differences in the Subject Alternative Name (SAN), leading to a policy bypass where a certificate that should be rejected is instead accepted. This could result in unauthorized access or information disclosure.
EPSS
6.5 Medium
CVSS3