CVE-2010-0555 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 5.01 SP4, 6, 6 SP1, 7, and 8 does not prevent rendering of non-HTML local files as HTML documents, which allows remote attackers to bypass intended access restrictions and read arbitrary files via vectors involving the product's use of text/html as the default content type for files that are encountered after a redirection, aka the URLMON sniffing vulnerability, a variant of CVE-2009-1140 and related to CVE-2008-1448.
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Analysis
by VulDB Data Team • 04/30/2026
The vulnerability described in CVE-2010-0555 represents a critical security flaw in Microsoft Internet Explorer versions 5.01 SP4 through 8, where the browser fails to properly validate file content types during rendering processes. This issue stems from the browser's default handling of content types, specifically when it encounters files that have been redirected through URLMON components. The vulnerability allows attackers to exploit the browser's content type sniffing behavior to render non-HTML files as HTML documents, effectively bypassing intended access controls and enabling unauthorized file access. This flaw operates under the broader category of content type confusion attacks, which are categorized under CWE-1004 in the Common Weakness Enumeration framework.
The technical execution of this vulnerability involves leveraging the URLMON component's default content type handling mechanism, which typically defaults to text/html for files encountered after redirection. When Internet Explorer processes a redirected file, it performs content type sniffing to determine how to render the content. However, this process fails to properly validate the actual file type, allowing attackers to craft malicious redirection scenarios where non-HTML files are rendered as HTML. The vulnerability is particularly dangerous because it enables attackers to read arbitrary files on the target system by exploiting the browser's trust in the default content type handling, making it a variant of the broader class of issues related to content type manipulation and file access bypass.
The operational impact of CVE-2010-0555 is significant, as it provides attackers with a method to circumvent file access restrictions that are typically enforced by operating system security mechanisms. This vulnerability can be exploited to read sensitive files such as configuration files, user data, or system information that should normally be protected from unauthorized access. The attack surface is particularly broad given that Internet Explorer 5.01 SP4 through 8 were widely deployed across enterprise environments, making this vulnerability a prime target for exploitation. The vulnerability's relationship to CVE-2009-1140 and CVE-2008-1448 demonstrates a pattern of content type sniffing flaws that have persisted across multiple browser versions and security contexts. Security researchers have noted that this vulnerability aligns with ATT&CK technique T1059.001 for command and scripting interpreter, as it enables attackers to potentially access system resources through browser-based attacks.
The exploitation of this vulnerability typically requires a malicious web page that redirects users to a file with a specific content type that can be manipulated through the browser's content sniffing behavior. Attackers can craft redirection scenarios where a file that is not actually HTML is rendered as such, potentially allowing access to local files that contain sensitive information. This vulnerability particularly affects environments where users may be tricked into visiting malicious websites that contain carefully crafted redirection sequences. Organizations should implement network-level protections such as web application firewalls and content filtering systems to prevent exploitation of this vulnerability, while also ensuring that users are properly educated about the risks of visiting untrusted websites. The vulnerability highlights the importance of proper content type validation and the need for robust input sanitization in browser security implementations.