CVE-2004-0760 in Mozilla
Summary
by MITRE
Mozilla allows remote attackers to cause Mozilla to open a URI as a different MIME type than expected via a null character (%00) in an FTP URI.
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Analysis
by VulDB Data Team • 09/27/2025
The vulnerability described in CVE-2004-0760 represents a critical input validation flaw within the Mozilla browser's handling of uniform resource identifiers. This issue specifically affects how Mozilla processes ftp URIs containing null characters, creating a potential vector for malicious exploitation. The vulnerability stems from the browser's inability to properly sanitize and validate URI components before processing them, particularly when null characters are embedded within ftp protocol identifiers. The flaw enables attackers to manipulate how the browser interprets file types during download operations, potentially leading to unexpected behavior and security consequences.
The technical implementation of this vulnerability involves the manipulation of ftp URI syntax through the insertion of null characters represented as %00 sequences within the URI structure. When Mozilla encounters such malformed URIs, the null character injection disrupts the normal parsing and type detection mechanisms that the browser uses to determine how to handle downloaded content. This disruption occurs because the null character acts as a delimiter that can cause the browser's MIME type detection system to misinterpret the intended file type, leading to the execution of content with incorrect assumptions about its nature. The vulnerability operates at the application layer and affects the browser's protocol handling capabilities, specifically targeting the ftp URI parser and subsequent content type determination processes.
The operational impact of this vulnerability extends beyond simple content misinterpretation to potentially enable more serious security exploits. Attackers could leverage this flaw to trick the browser into executing malicious content by causing it to treat executable files as benign text or image formats, or conversely, to treat benign files as executable. This type of manipulation could facilitate various attack vectors including drive-by downloads, cross-site scripting attempts, or other content-based attacks that rely on proper MIME type handling. The vulnerability particularly affects users who frequently interact with ftp resources or download content from untrusted sources, as the attack requires only the presentation of a maliciously crafted URI to the browser.
Mitigation strategies for this vulnerability should focus on implementing robust input validation and sanitization measures within the browser's URI parsing components. Security patches would need to address the specific handling of null characters within ftp URIs by ensuring proper validation before any MIME type determination occurs. Organizations should implement comprehensive browser security policies that include regular updates and patches, network monitoring for suspicious URI patterns, and user education regarding the dangers of visiting untrusted websites or downloading content from unknown sources. The vulnerability aligns with CWE-170, which addresses improper handling of null characters, and represents a specific instance of how protocol parsing flaws can be exploited for content type confusion attacks. This vulnerability also relates to ATT&CK technique T1059, which covers command and scripting interpreters, as the potential for executing unintended content through MIME type manipulation could enable code execution in compromised environments.