CVE-2020-6826 in Firefox
Summary
by MITRE
Mozilla developers Tyson Smith, Bob Clary, and Alexandru Michis reported memory safety bugs present in Firefox 74. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 75.
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Analysis
by VulDB Data Team • 05/06/2025
The vulnerability identified as CVE-2020-6826 represents a critical memory safety issue within the Mozilla Firefox browser that was present in versions prior to 75. This flaw emerged from a collection of memory safety bugs discovered by security researchers Tyson Smith, Bob Clary, and Alexandru Michis, highlighting the ongoing challenges in maintaining secure browser implementations. The reported bugs demonstrate evidence of memory corruption that could potentially be leveraged by attackers to execute arbitrary code on affected systems. These memory safety issues are particularly concerning because they represent fundamental weaknesses in how Firefox handles memory allocation and deallocation processes, creating potential entry points for malicious actors.
The technical nature of this vulnerability stems from memory corruption flaws that can occur when Firefox processes certain web content or executes specific JavaScript operations. Memory corruption vulnerabilities typically arise when applications fail to properly validate input data or manage memory resources, leading to situations where attackers can manipulate memory layout to execute malicious code. These types of vulnerabilities are classified under CWE-125 as "Out-of-bounds Read" and CWE-787 as "Out-of-bounds Write" in the Common Weakness Enumeration catalog, which are common patterns in browser security exploits. The vulnerability affects Firefox versions less than 75, indicating that the memory safety issues were present in the browser's rendering engine and JavaScript engine implementations, particularly in how they handle complex web page interactions and dynamic content processing.
The operational impact of CVE-2020-6826 extends beyond simple browser instability, as it creates potential attack vectors that could be exploited in real-world scenarios. When memory corruption occurs in browser contexts, attackers can potentially leverage these flaws to bypass security mechanisms such as address space layout randomization and data execution prevention. This vulnerability aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: JavaScript" and T1071.004 for "Application Layer Protocol: DNS" as attackers might use compromised browsers to establish command and control communications. The potential for arbitrary code execution means that users could be vulnerable to drive-by downloads, malicious website exploitation, or other attack vectors that take advantage of the browser's memory handling weaknesses. Organizations using affected Firefox versions face significant risk of compromise, as these vulnerabilities could be exploited through standard web browsing activities without user interaction.
The recommended mitigation for CVE-2020-6826 involves immediate upgrade to Firefox version 75 or later, which contains the necessary patches to address the reported memory safety bugs. System administrators should prioritize deployment of this update across all affected systems, particularly in enterprise environments where browser security is critical. Additional protective measures include implementing browser hardening configurations, enabling security features such as sandboxing and content filtering, and conducting regular security assessments to identify potential exploitation attempts. The vulnerability demonstrates the importance of continuous security monitoring and timely patch management, as memory safety issues often remain undetected until exploited in the wild. Organizations should also consider implementing network-level protections such as web application firewalls and intrusion detection systems to monitor for exploitation attempts targeting this vulnerability. The incident underscores the necessity of maintaining up-to-date security practices and the critical role that browser vendors play in addressing memory safety concerns that could compromise user systems.