CVE-2010-0652 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer permits cross-origin loading of CSS stylesheets even when the stylesheet download has an incorrect MIME type and the stylesheet document is malformed, which allows remote HTTP servers to obtain sensitive information via a crafted document.
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Analysis
by VulDB Data Team • 05/01/2026
This vulnerability in Microsoft Internet Explorer represents a significant security flaw that exploits the browser's permissive handling of cross-origin resources despite incorrect MIME type detection. The issue stems from the browser's failure to properly validate the content type of downloaded stylesheet resources, allowing malicious remote servers to serve malformed CSS content with incorrect MIME headers while still having the content loaded and processed by the browser. The vulnerability specifically affects the CSS stylesheet loading mechanism where Internet Explorer bypasses normal security restrictions when encountering improperly formatted stylesheet documents, creating an attack surface for information disclosure.
The technical flaw resides in the browser's Content Security Policy enforcement and cross-origin resource loading behavior. When Internet Explorer encounters a CSS stylesheet from a different origin, it typically applies strict MIME type checking to prevent loading of content that doesn't match the expected application/css content type. However, this validation mechanism fails when the stylesheet contains malformed content that can still be processed by the browser's CSS parser, even when the MIME type is incorrect. This creates a scenario where remote attackers can craft malicious documents that trigger the browser to load and process CSS content from arbitrary origins, potentially exposing sensitive information through the cross-origin resource loading behavior.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables attackers to leverage the browser's CSS processing capabilities to extract data from other domains or origins. The flaw can be exploited through malicious web pages that reference external CSS resources with incorrect MIME types, allowing attackers to potentially gather information about the victim's browsing context, session data, or other sensitive resources that might be accessible through cross-origin CSS loading. This vulnerability particularly affects users of older Internet Explorer versions where the security model was less restrictive regarding cross-origin resource handling. The attack vector typically involves crafting HTML documents that include external CSS references, where the remote server responds with malformed CSS content that triggers the vulnerable behavior in the browser's CSS engine.
This vulnerability maps to CWE-16 Configuration and CWE-200 Information Exposure, representing weaknesses in software configuration and improper information exposure. The attack pattern aligns with techniques described in the MITRE ATT&CK framework under T1059 Command and Scripting Interpreter and T1566 Phishing, where attackers leverage browser vulnerabilities to execute malicious code or extract information. The vulnerability also relates to T1213 Data from Information Repositories, as it allows for the unauthorized access to information that should be protected by cross-origin security restrictions. Organizations should implement browser security updates, disable unnecessary cross-origin resource loading, and deploy network-based security controls to mitigate this vulnerability. The recommended mitigations include applying Microsoft security patches, configuring browser security policies to restrict cross-origin CSS loading, and implementing content security policies that limit external resource loading from untrusted origins. Additionally, users should be educated about avoiding suspicious web content and keeping their browsers updated to prevent exploitation of this and similar cross-origin resource loading vulnerabilities.