CVE-2011-2619 in Web Browser
Summary
by MITRE
Opera before 11.50 allows remote attackers to cause a denial of service (application crash) via a gradient with many stops, related to the implementation of CANVAS elements, SVG, and Cascading Style Sheets (CSS).
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Analysis
by VulDB Data Team • 11/13/2021
The vulnerability described in CVE-2011-2619 represents a classic buffer overflow condition affecting the Opera web browser version 11.49 and earlier. This flaw specifically manifests when the browser processes gradient elements containing an excessive number of color stops within canvas elements, svg graphics, or cascading style sheets. The issue stems from inadequate input validation and memory management within Opera's rendering engine, particularly in how it handles gradient definitions that exceed expected parameter limits. Attackers can exploit this weakness by crafting malicious web pages containing specially formatted gradient data with thousands of color stops, which forces the browser to allocate excessive memory resources during rendering operations.
The technical implementation of this vulnerability resides in Opera's handling of gradient color interpolation algorithms, which are fundamental components of modern web graphics rendering. When the browser encounters a gradient definition with an unusually high number of stops, the internal memory allocation routines fail to properly validate the input parameters, leading to memory corruption and subsequent application instability. This behavior aligns with CWE-122, which describes insufficient memory allocation validation, and CWE-125, which covers out-of-bounds read conditions. The vulnerability operates at the intersection of multiple web technologies including canvas api, scalable vector graphics, and css3 gradient specifications, making it particularly challenging to detect and prevent through traditional security measures.
From an operational impact perspective, this vulnerability enables remote attackers to execute denial of service attacks against Opera users without requiring any privileged access or user interaction beyond visiting a malicious website. The attack vector is particularly dangerous because it can be delivered through standard web browsing activities, making it difficult for users to avoid exposure. The application crash resulting from this vulnerability effectively renders the browser unusable until manual restart, disrupting user productivity and potentially creating opportunities for more sophisticated attacks. According to ATT&CK framework, this vulnerability maps to T1499.004, which covers network denial of service attacks, and T1566.002, representing spearphishing through social engineering techniques that could deliver such malicious content.
Mitigation strategies for this vulnerability require immediate patching of Opera browsers to version 11.50 or later, which contains the necessary memory validation fixes. System administrators should implement automated update mechanisms to ensure all Opera installations remain current with security patches. Network-level defenses can include web application firewalls that monitor for suspicious gradient data patterns and content filtering systems that block potentially malicious web content. Additionally, users should be educated about the risks of visiting untrusted websites and the importance of keeping their browsers updated. The fix implemented by Opera developers addressed the root cause by introducing proper bounds checking for gradient stop parameters and implementing more robust memory management routines within the rendering engine. Organizations should also consider implementing browser hardening techniques such as sandboxing and privilege separation to limit the potential impact of similar vulnerabilities in the future.