CVE-2006-5462 in Firefox
Summary
by MITRE
Mozilla Network Security Service (NSS) library before 3.11.3, as used in Mozilla Firefox before 1.5.0.8, Thunderbird before 1.5.0.8, and SeaMonkey before 1.0.6, when using an RSA key with exponent 3, does not properly handle extra data in a signature, which allows remote attackers to forge signatures for SSL/TLS and email certificates. NOTE: this identifier is for unpatched product versions that were originally intended to be addressed by CVE-2006-4340.
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Analysis
by VulDB Data Team • 04/27/2026
The vulnerability described in CVE-2006-5462 represents a critical flaw in the Mozilla Network Security Service library that affected multiple Mozilla products including Firefox, Thunderbird, and SeaMonkey. This issue specifically targets the handling of RSA signatures with exponent 3, creating a significant security weakness that could be exploited by remote attackers to forge digital signatures for SSL/TLS certificates and email certificates. The vulnerability stems from improper validation of signature data, particularly when extra data is present in the signature structure. This flaw allowed malicious actors to manipulate signature verification processes and potentially compromise the integrity of secure communications.
The technical root cause of this vulnerability lies in the insufficient validation of signature data within the NSS library implementation. When RSA keys with exponent 3 are used, the system fails to properly validate that all signature data is correctly formatted and that no extraneous data is present. This improper handling creates a window where attackers can craft forged signatures that bypass normal verification procedures. The vulnerability specifically affects systems using RSA keys with a small exponent value of 3, which is often used for performance optimization but introduces additional security risks when not properly validated. This issue is categorized under CWE-20, which deals with improper input validation, and represents a classic example of how cryptographic implementation flaws can lead to serious security breaches.
The operational impact of this vulnerability is severe as it directly undermines the trust model of SSL/TLS and email security systems. Remote attackers could exploit this weakness to create fraudulent certificates that would appear legitimate to users and systems, potentially enabling man-in-the-middle attacks, unauthorized access to secure communications, and compromise of email systems. The vulnerability affects widely deployed software products, making it particularly dangerous as it could impact millions of users across multiple platforms. The security implications extend beyond simple certificate forgery to potentially allow complete compromise of secure communication channels, as the forged certificates could be used to intercept and modify encrypted data without detection.
Organizations and users affected by this vulnerability should immediately upgrade to patched versions of their Mozilla products, specifically ensuring Firefox is updated to version 1.5.0.8 or later, Thunderbird to 1.5.0.8 or later, and SeaMonkey to 1.0.6 or later. The patch addresses the core issue by implementing proper signature data validation that rejects signatures containing extra data or malformed structures. Additionally, system administrators should review certificate trust stores and consider revoking any certificates that may have been compromised. This vulnerability aligns with ATT&CK technique T1556.002 which covers credential harvesting through certificate manipulation, and demonstrates the importance of proper cryptographic implementation practices. Organizations should also implement monitoring for suspicious certificate activity and consider network segmentation to limit the potential impact of any successful exploitation attempts. The incident highlights the critical need for thorough testing of cryptographic implementations and proper validation of all signature data to prevent similar vulnerabilities from being introduced in future software releases.