CVE-2010-0063 in Mac OS X
Summary
by MITRE
Incomplete blacklist vulnerability in CoreTypes in Apple Mac OS X before 10.6.3 makes it easier for user-assisted remote attackers to execute arbitrary JavaScript via a web page that offers a download with a Content-Type value that is not on the list of possibly unsafe content types for Safari, as demonstrated by the values for the (1) .ibplugin and (2) .url extensions.
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Analysis
by VulDB Data Team • 05/03/2026
The vulnerability identified as CVE-2010-0063 represents a critical security flaw in Apple Mac OS X operating systems prior to version 10.6.3, specifically within the CoreTypes framework responsible for handling file type associations and content filtering. This weakness stems from an incomplete blacklist implementation that fails to adequately restrict potentially dangerous file extensions, creating an exploitable gap in Safari's security model. The vulnerability manifests when web pages attempt to deliver files with specific extensions that should be treated as potentially malicious but are not properly filtered by the browser's content type validation mechanisms.
The technical implementation of this flaw resides in the CoreTypes component's content type handling logic where certain file extensions including .ibplugin and .url are not properly included in the blacklist of unsafe content types. This incomplete filtering allows attackers to craft malicious web pages that present downloads with these specific extensions, bypassing Safari's built-in security protections. The vulnerability operates under the principle of insufficient blacklist validation, which is categorized under CWE-172 in the Common Weakness Enumeration framework, specifically addressing improper restriction of potentially dangerous content types.
From an operational perspective, this vulnerability creates a significant risk for Mac OS X users as it enables remote code execution through seemingly benign web interactions. Attackers can leverage this weakness by hosting malicious content that appears legitimate but contains the targeted file extensions, tricking users into downloading and executing arbitrary JavaScript code. The user-assisted nature of this attack means that successful exploitation requires some form of user interaction, typically through clicking on a malicious link or download, but the underlying flaw in the content filtering system makes such attacks more feasible than they should be.
The impact of this vulnerability extends beyond simple script execution, as it represents a fundamental flaw in the operating system's security architecture that could potentially be exploited to gain deeper system access. The fact that this issue affects Safari's core content handling mechanisms means that it could be leveraged for more sophisticated attacks, including those involving privilege escalation or persistent malware installation. This vulnerability aligns with ATT&CK technique T1059.007 for JavaScript execution and represents a classic example of how incomplete security controls can create dangerous attack vectors in web browsers.
Organizations and individual users affected by this vulnerability should immediately update to Mac OS X 10.6.3 or later versions where Apple has implemented proper blacklist validation for the identified content types. Additionally, network administrators should consider implementing additional content filtering measures and user education programs to reduce the risk of successful exploitation. The vulnerability serves as a reminder of the importance of comprehensive security testing and the need for robust content type validation in web browsers and operating systems. Security teams should also monitor for similar patterns in other applications that rely on similar content filtering mechanisms and ensure that all potentially dangerous file extensions are properly accounted for in security policies.