CVE-2011-0473 in Chrome
Summary
by MITRE
Google Chrome before 8.0.552.237 and Chrome OS before 8.0.552.344 do not properly handle Cascading Style Sheets (CSS) token sequences in conjunction with CANVAS elements, which allows remote attackers to cause a denial of service or possibly have unspecified other impact via unknown vectors that lead to a "stale pointer."
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Analysis
by VulDB Data Team • 10/12/2021
This vulnerability exists in Google Chrome versions prior to 8.0.552.237 and Chrome OS versions prior to 8.0.552.344, representing a critical security flaw in the browser's handling of Cascading Style Sheets token sequences combined with CANVAS elements. The issue stems from improper memory management during CSS processing, specifically when the browser encounters certain token sequences that interact with canvas rendering components. The vulnerability manifests as a stale pointer condition, where memory references become invalid while still being accessed by the browser's rendering engine. This flaw falls under the CWE-462 category of "Use of a Deferred Pointer" and represents a classic memory safety issue that can lead to unpredictable behavior in the application's execution flow.
The technical exploitation of this vulnerability occurs when malicious web content presents carefully crafted CSS token sequences alongside CANVAS elements that trigger the browser's rendering engine to access memory locations that have already been freed or reallocated. When Chrome processes these specific combinations, the CSS parser and canvas rendering components interact in a way that leaves dangling pointers in memory, which can be exploited to cause system instability. The stale pointer condition allows attackers to potentially manipulate memory contents or force the browser to crash, resulting in a denial of service attack. According to ATT&CK framework, this vulnerability maps to T1203 "Exploitation for Client Execution" and T1499 "Endpoint Denial of Service" as it enables remote code execution through browser exploitation and system resource exhaustion.
The operational impact of this vulnerability extends beyond simple denial of service, as the stale pointer condition creates potential for more severe consequences including arbitrary code execution in the browser context. Attackers can craft malicious web pages that, when loaded in affected Chrome versions, trigger the memory corruption scenario and potentially lead to full system compromise. The vulnerability affects a wide range of users since Chrome was and remains one of the most widely used web browsers globally, making the attack surface extremely large. Organizations using Chrome-based applications for web browsing, content management, or web application access face significant risk from this vulnerability. The issue demonstrates the complexity of modern browser security where interactions between different rendering components can create unexpected memory access patterns that lead to exploitable conditions.
Mitigation strategies for this vulnerability require immediate patching of affected Chrome versions to the latest stable releases, which contain memory safety improvements and proper handling of CSS token sequences. Organizations should implement browser hardening measures including sandboxing, content security policies, and regular security updates to reduce the attack surface. Network administrators should consider implementing web filtering solutions to block access to potentially malicious domains that might host exploit code. The vulnerability highlights the importance of proper memory management in browser engines and the need for continuous security testing of rendering components. Regular security assessments should include memory safety testing of CSS parsers and canvas rendering engines to identify similar stale pointer conditions before they can be exploited in the wild. This particular vulnerability underscores the critical nature of browser security in enterprise environments where web-based attacks represent one of the most common attack vectors.