CVE-2016-2819 in Firefox
Summary
by MITRE
Heap-based buffer overflow in Mozilla Firefox before 47.0 and Firefox ESR 45.x before 45.2 allows remote attackers to execute arbitrary code via foreign-context HTML5 fragments, as demonstrated by fragments within an SVG element.
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Analysis
by VulDB Data Team • 10/23/2024
The heap-based buffer overflow vulnerability identified as CVE-2016-2819 represents a critical security flaw in Mozilla Firefox browsers prior to version 47.0 and Firefox ESR 45.x before version 45.2. This vulnerability exists within the browser's handling of HTML5 fragments in foreign contexts, specifically when processing SVG elements that contain maliciously crafted content. The flaw stems from inadequate bounds checking during the parsing and rendering of HTML5 fragments, creating an exploitable condition where attacker-controlled data can overwrite adjacent memory locations in the heap allocation space. The vulnerability is particularly dangerous because it allows remote code execution without requiring user interaction beyond visiting a malicious webpage, making it a prime target for drive-by download attacks and social engineering campaigns.
The technical implementation of this vulnerability involves the improper handling of HTML5 fragments within SVG elements, which creates a scenario where the browser's memory management system fails to properly validate the size and boundaries of data being processed. When Firefox encounters HTML5 fragments within an SVG context, the parser does not adequately enforce memory limits, allowing an attacker to craft malicious content that exceeds the allocated buffer size. This overflow can corrupt adjacent heap memory, potentially enabling attackers to overwrite function pointers, return addresses, or other critical program data structures. The vulnerability is classified under CWE-121 as a heap-based buffer overflow, which is a well-documented weakness in memory management where data written beyond the allocated buffer can overwrite adjacent memory regions, leading to arbitrary code execution.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass a broad range of attack vectors that can compromise user systems and data integrity. Attackers can leverage this flaw to inject malicious code that executes with the privileges of the browser process, potentially leading to full system compromise. The vulnerability's exploitation within SVG elements makes it particularly insidious as SVG is commonly used in web graphics and can be embedded in various web pages without raising immediate suspicion. Security researchers have documented this vulnerability as part of the broader ATT&CK framework under techniques related to code injection and privilege escalation, where attackers can use such flaws to establish persistent access to compromised systems. The vulnerability affects not only individual users but also organizations that rely on Firefox for business operations, potentially leading to data breaches, credential theft, and unauthorized access to sensitive information.
Organizations and users should immediately update to Firefox versions 47.0 or later for regular releases and 45.2 or later for ESR releases to mitigate this vulnerability. The update process should be prioritized as a critical security measure, particularly in enterprise environments where multiple users access potentially malicious websites. Additional defensive measures include implementing web application firewalls, deploying content security policies that restrict SVG processing, and monitoring for suspicious network traffic patterns that may indicate exploitation attempts. Security teams should also consider implementing browser hardening measures such as disabling unnecessary browser features, using sandboxing technologies, and regularly auditing web content for malicious fragments. The vulnerability demonstrates the importance of maintaining up-to-date software and highlights the critical need for continuous security monitoring and rapid response to emerging threats in the browser ecosystem.