CVE-2020-6800 in Firefox
Summary
by MITRE
Mozilla developers and community members reported memory safety bugs present in Firefox 72 and Firefox ESR 68.4. 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. In general, these flaws cannot be exploited through email in the Thunderbird product because scripting is disabled when reading mail, but are potentially risks in browser or browser-like contexts. This vulnerability affects Thunderbird < 68.5, Firefox < 73, and Firefox < ESR68.5.
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Analysis
by VulDB Data Team • 05/11/2025
This vulnerability represents a collection of memory safety issues discovered in Mozilla Firefox and Thunderbird products, specifically affecting versions prior to 73.0 for Firefox and 68.5 for Thunderbird and Firefox ESR 68.4. The reported bugs demonstrate evidence of memory corruption which could potentially be exploited to execute arbitrary code on affected systems. These memory safety flaws fall under the broader category of software vulnerabilities that can lead to serious security implications when properly exploited. The presence of memory corruption issues in browser environments creates significant risks as they can be leveraged by attackers to gain unauthorized control over user systems.
The technical nature of these vulnerabilities stems from improper memory handling within the browser's rendering and processing engines. When applications fail to properly manage memory allocation, deallocation, or access patterns, they become susceptible to various forms of memory corruption including buffer overflows, use-after-free conditions, and heap corruption. These specific bugs were identified in the Firefox browser engine and its associated components, particularly affecting the JavaScript engine and related memory management systems. The vulnerability classification aligns with common weakness enumerations such as CWE-121, which addresses stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow conditions.
The operational impact of these vulnerabilities extends beyond simple security concerns to encompass potential system compromise and data exposure risks. While the vulnerability cannot be exploited through email in Thunderbird due to scripting being disabled during mail reading, the threat remains significant in browser contexts where active content execution is permitted. This distinction places the risk squarely within the realm of web-based attacks where users might encounter malicious content through compromised websites, phishing campaigns, or drive-by downloads. The potential for arbitrary code execution means that successful exploitation could result in complete system compromise, data theft, or the installation of persistent malware on affected systems.
Security practitioners should consider these vulnerabilities in relation to the attack mitigation framework, particularly focusing on the initial access and execution phases of the kill chain. The ATT&CK framework categorizes such vulnerabilities under the technique of "Exploitation for Client Execution" where attackers leverage software vulnerabilities to execute malicious code on target systems. Organizations should prioritize patch management to ensure all affected versions of Firefox and Thunderbird are updated promptly. The recommended mitigations include immediate deployment of security patches, implementation of web application firewalls, and enhanced user awareness training to avoid visiting compromised websites or clicking on suspicious links. Additionally, system administrators should consider implementing network-based monitoring to detect potential exploitation attempts and maintain up-to-date threat intelligence to stay informed about related attack vectors and techniques that may leverage similar memory corruption vulnerabilities.