CVE-2011-2621 in Web Browser
Summary
by MITRE
Unspecified vulnerability in Opera before 11.50 allows remote attackers to cause a denial of service (application crash) via vectors related to form layout.
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Analysis
by VulDB Data Team • 11/13/2021
The vulnerability identified as CVE-2011-2621 represents a denial of service flaw affecting Opera web browsers prior to version 11.50. This issue manifests when remote attackers exploit specific conditions related to form layout handling within the browser's rendering engine. The vulnerability falls under the category of unspecified vulnerability types, indicating that the exact technical mechanism was not fully detailed in the initial reporting. Such unspecified nature often suggests complex interactions between multiple browser components or subtle parsing behaviors that can lead to unexpected application states.
The technical flaw resides in Opera's handling of form elements during layout calculations, where malformed or specially crafted form structures can trigger memory corruption or invalid state transitions within the browser's rendering pipeline. This typically occurs when the browser attempts to process complex form layouts that exceed expected parameter boundaries or contain unexpected element combinations. The vulnerability leverages the browser's form parsing and layout engine to create conditions that result in application instability. According to CWE categorization, this vulnerability aligns with CWE-121, which deals with stack-based buffer overflow conditions, and potentially CWE-122, heap-based buffer overflow conditions, though the exact mechanism requires deeper analysis of the specific form layout constructs that trigger the issue.
Operationally, this vulnerability presents significant risk to users who may encounter unexpected browser crashes when navigating to malicious websites or viewing specially crafted web pages containing problematic form elements. The denial of service impact can disrupt user productivity and potentially serve as a precursor to more sophisticated attacks if attackers can chain this vulnerability with other exploits. Users running Opera versions before 11.50 face elevated risk when browsing untrusted websites, particularly those containing user-generated content or forms that may have been manipulated to exploit this flaw. The vulnerability can be exploited through various vectors including web pages with embedded forms, dynamically generated content, or even through cross-site scripting scenarios where attackers can inject malicious form structures into legitimate websites.
The mitigation strategy for CVE-2011-2621 centers on upgrading to Opera version 11.50 or later, which contains the necessary patches to address the form layout handling issues. System administrators should prioritize this update across all affected systems, particularly in enterprise environments where Opera browsers are in use. Additional defensive measures include implementing web application firewalls that can detect and block suspicious form structures, enabling browser security features such as sandboxing, and maintaining regular security updates for all browser components. From an ATT&CK framework perspective, this vulnerability could be categorized under T1499.004 for network denial of service and potentially T1566.001 for initial access through malicious web content, making it a critical component in understanding attack chains that begin with web-based delivery mechanisms. Organizations should also consider implementing browser hardening configurations and monitoring for unusual browser crash patterns that might indicate exploitation attempts.