CVE-2014-1492 in Network Security Services
Summary
by MITRE
The cert_TestHostName function in lib/certdb/certdb.c in the certificate-checking implementation in Mozilla Network Security Services (NSS) before 3.16 accepts a wildcard character that is embedded in an internationalized domain name's U-label, which might allow man-in-the-middle attackers to spoof SSL servers via a crafted certificate.
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Analysis
by VulDB Data Team • 05/09/2026
The vulnerability described in CVE-2014-1492 represents a critical flaw in Mozilla Network Security Services NSS library that affects certificate validation mechanisms. This issue specifically targets the cert_TestHostName function within the certificate database component, which is responsible for validating hostnames against SSL/TLS certificates. The vulnerability stems from an insufficient validation process that fails to properly handle wildcard characters within internationalized domain names, creating a significant security gap that could be exploited by malicious actors.
The technical flaw occurs when the certificate validation function processes internationalized domain names using U-labels, which are Unicode representations of domain names that can contain wildcard characters. The function does not adequately sanitize or validate these embedded wildcard characters, allowing an attacker to craft a certificate that appears valid but actually contains a wildcard that should not be permitted in the context of certificate validation. This flaw specifically affects the comparison logic between the certificate's subject alternative name and the actual hostname being accessed, creating a path for certificate forgery attacks.
The operational impact of this vulnerability is severe as it enables man-in-the-middle attackers to successfully spoof SSL servers by presenting certificates that would otherwise be rejected by proper validation mechanisms. Attackers can exploit this weakness by creating certificates with wildcard characters embedded within internationalized domain names, making the forged certificates appear legitimate to systems using affected NSS versions. This vulnerability directly undermines the fundamental security assurances provided by SSL/TLS certificate validation, potentially allowing attackers to intercept and manipulate encrypted communications between clients and servers.
This vulnerability maps to CWE-295 which specifically addresses "Improper Certificate Validation" and aligns with ATT&CK technique T1552.001 for "Unsecured Credentials" and T1046 for "Network Service Scanning" as attackers could use this weakness to establish unauthorized connections. The flaw represents a failure in the certificate validation process that should have prevented the acceptance of certificates with malformed wildcard patterns within internationalized domain names. Organizations using NSS versions prior to 3.16 are particularly vulnerable as the patch for this issue was released as part of the NSS 3.16 update, which properly addressed the validation logic to reject wildcard characters embedded within U-labels. The recommended mitigation strategy involves upgrading to NSS 3.16 or later versions that contain the necessary validation fixes to prevent certificate forgery attacks through this specific pathway.
The broader implications of this vulnerability extend beyond immediate exploitation capabilities to highlight systemic issues in internationalized domain name handling within cryptographic libraries. This flaw demonstrates the complexity of validating internationalized domain names while maintaining proper security boundaries, particularly when wildcard characters are involved in Unicode domain representations. The vulnerability underscores the importance of comprehensive testing for internationalized domain name handling in security-critical components and the necessity of proper input sanitization for all domain name components within certificate validation processes. Organizations should conduct thorough assessments of their systems using affected NSS versions to identify potential exposure and implement immediate patching measures to protect against this specific class of certificate validation attacks.