CVE-2006-4310 in Firefox
Summary
by MITRE
Mozilla Firefox 1.5.0.6 allows remote attackers to cause a denial of service (crash) via a crafted FTP response, when attempting to connect with a username and password via the FTP URI.
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Analysis
by VulDB Data Team • 05/25/2025
The vulnerability described in CVE-2006-4310 represents a denial of service flaw affecting Mozilla Firefox version 1.5.0.6 specifically when processing FTP URIs with authentication credentials. This issue arises from insufficient input validation within the browser's FTP handling mechanism, creating a condition where maliciously crafted FTP responses can trigger unexpected behavior in the application's network processing stack. The vulnerability operates at the intersection of web browser security and network protocol handling, demonstrating how seemingly benign URI parsing can become a vector for service disruption.
The technical exploitation of this vulnerability occurs when Firefox attempts to establish an FTP connection using a URI containing username and password credentials. During the connection process, the browser receives a malformed FTP response that contains unexpected data structures or malformed control sequences. The browser's FTP parser fails to properly validate or sanitize incoming response data, leading to an unhandled exception that causes the application to crash and terminate unexpectedly. This flaw falls under the category of improper input validation as defined by CWE-20, where the application processes input without adequate checks for malformed or unexpected data.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be leveraged by remote attackers to systematically crash Firefox instances through crafted web content or malicious FTP servers. An attacker could construct a malicious webpage containing an FTP URI with specially crafted credentials that, when clicked or loaded by a victim, would trigger the crash. This creates a potential for widespread disruption in environments where users frequently access web content, particularly in corporate or educational settings where Firefox is commonly deployed. The vulnerability specifically targets the browser's FTP handling functionality rather than its core rendering engine, making it more targeted but still capable of causing significant user experience degradation.
Security professionals should note that this vulnerability aligns with ATT&CK technique T1499.001 which covers network denial of service attacks. The flaw represents a classic case of a buffer overflow or memory corruption issue that occurs during protocol parsing, though it manifests as a crash rather than arbitrary code execution. Organizations should implement immediate mitigations including updating to Firefox 1.5.0.7 or later versions where this vulnerability has been patched, as well as monitoring network traffic for suspicious FTP response patterns that might indicate exploitation attempts. Network administrators should also consider implementing web filtering measures to block access to known malicious FTP resources until full patch deployment is complete. The vulnerability serves as a reminder of the importance of robust input validation in network protocol implementations and the critical need for regular security updates in web browsers.