CVE-2007-0995 in Web Browser
Summary
by MITRE
Mozilla Firefox before 1.5.0.10 and 2.x before 2.0.0.2, and SeaMonkey before 1.0.8 ignores trailing invalid HTML characters in attribute names, which allows remote attackers to bypass content filters that use regular expressions.
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Analysis
by VulDB Data Team • 03/15/2021
This vulnerability affects mozilla firefox versions prior to 1.5.0.10 and 2.x versions prior to 2.0.0.2, as well as seamonkey versions before 1.0.8, where the browser fails to properly validate html attribute names by ignoring trailing invalid characters. the technical flaw resides in the html parser implementation which does not strictly enforce attribute name validation, allowing attackers to craft malicious html content that contains trailing invalid characters after attribute names. this behavior creates a bypass mechanism for content filtering systems that rely on regular expression patterns to detect and block malicious content, as the parser accepts the malformed attributes while the filter may not recognize them as potentially dangerous. the operational impact is significant as it enables remote attackers to circumvent security controls designed to prevent cross site scripting attacks and other html injection vulnerabilities. attackers can exploit this weakness by embedding malicious attributes with trailing invalid characters that appear to be valid to the content filter but are actually processed by the browser's html parser in a way that may execute unintended code or bypass security restrictions. this vulnerability is classified under cwe-1071 which deals with improper handling of invalid input, and relates to attack technique t1071.004 in the attack framework which covers application layer protocol manipulation. the bypass occurs because the regular expression based filters do not account for the html parser's lenient handling of trailing invalid characters, creating a mismatch between the filtering logic and the actual parsing behavior. organizations using these vulnerable browsers should prioritize immediate updates to prevent exploitation of this bypass mechanism. the fix implemented in the patched versions ensures that html attribute names are strictly validated, eliminating the trailing character handling that enables the bypass. security teams should also review their content filtering systems to ensure they account for browser parsing behaviors and implement more robust validation mechanisms that consider the actual processing of html content rather than just surface level pattern matching. this vulnerability demonstrates the importance of consistent security validation across all layers of web application processing, from content filtering to browser parsing, and highlights the need for comprehensive testing that considers how different components interact with malformed input. the issue represents a classic case of security controls being bypassed due to inconsistent handling of edge cases between different software components, particularly in the area of html parsing and validation where the behavior of different parsers can create unexpected security implications.