CVE-2010-1029 in Chrome
Summary
by MITRE
Stack consumption vulnerability in the WebCore::CSSSelector function in WebKit, as used in Apple Safari 4.0.4, Apple Safari on iPhone OS and iPhone OS for iPod touch, and Google Chrome 4.0.249, allows remote attackers to cause a denial of service (application crash) or possibly execute arbitrary code via a STYLE element composed of a large number of *> sequences.
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Analysis
by VulDB Data Team • 05/03/2026
The vulnerability identified as CVE-2010-1029 represents a critical stack consumption flaw within the WebKit rendering engine's CSS selector processing mechanism. This vulnerability specifically affects the WebCore::CSSSelector function which is responsible for parsing and interpreting CSS selectors in web documents. The issue manifests when the parser encounters a STYLE element containing an excessive number of *> sequences, which are CSS descendant combinators that reference parent elements. This particular flaw demonstrates how seemingly benign CSS syntax can be exploited to trigger catastrophic stack exhaustion conditions in web browsers.
The technical exploitation of this vulnerability occurs through a carefully crafted CSS selector structure that creates deeply nested parsing operations within the WebKit engine's CSS selector parser. When the WebCore::CSSSelector function processes a malformed STYLE element containing numerous *> sequences, it recursively traverses the selector tree in a manner that consumes excessive stack memory. This recursive parsing approach, combined with the lack of proper stack depth limits or overflow protections, allows an attacker to construct CSS content that systematically depletes the available stack space. The vulnerability falls under the CWE-674 category of Uncontrolled Recursion, where recursive processing without adequate safeguards leads to resource exhaustion. The attack vector is particularly insidious because it requires no user interaction beyond visiting a malicious webpage, making it a prime candidate for automated exploitation.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable arbitrary code execution in affected browsers. When the stack consumption reaches critical levels, the application crashes due to stack overflow, resulting in a denial of service that disrupts user browsing experience. However, in certain circumstances where the stack overflow occurs in a manner that allows memory corruption, attackers may be able to manipulate the execution flow to achieve code execution. This vulnerability affects multiple high-profile browser implementations including Apple Safari versions 4.0.4 and earlier, iPhone OS Safari, and Google Chrome 4.0.249 and earlier versions, representing a significant attack surface across mobile and desktop platforms. The vulnerability demonstrates the importance of proper input validation and resource management in parsing libraries, as the issue originates from inadequate bounds checking during CSS selector parsing operations.
Mitigation strategies for this vulnerability require immediate patching of affected browser versions to implement proper stack depth limits and recursive parsing safeguards. Browser vendors should implement stack overflow protection mechanisms that prevent excessive recursion during CSS parsing operations, as well as introduce input sanitization that limits the complexity of CSS selectors that can be processed. The fix should include implementing a maximum nesting depth for CSS selectors and ensuring that recursive parsing operations respect these limits to prevent stack exhaustion. From an operational security perspective, organizations should prioritize updating all affected browser installations and implement web application firewalls that can detect and block malicious CSS content containing excessive *> sequences. The vulnerability also highlights the need for comprehensive security testing of parsing libraries and the importance of adhering to ATT&CK framework principles for defensive measures against such parsing-based attacks. Network administrators should monitor for suspicious web traffic patterns and consider implementing content filtering measures that can identify and neutralize potentially malicious CSS constructs before they reach end-user browsers.