CVE-2016-9893 in Firefox
Summary
by MITRE
Memory safety bugs were reported in Thunderbird 45.5. Some of these bugs showed evidence of memory corruption and we presume that with enough effort that some of these could be exploited to run arbitrary code. This vulnerability affects Firefox < 50.1, Firefox ESR < 45.6, and Thunderbird < 45.6.
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Analysis
by VulDB Data Team • 11/25/2025
The vulnerability identified as CVE-2016-9893 represents a critical memory safety issue discovered in Mozilla Thunderbird version 45.5 and related browser products. This vulnerability category falls under the broader classification of memory corruption flaws that have historically proven to be among the most dangerous security weaknesses in software applications. The reported memory safety bugs demonstrate evidence of memory corruption, which creates opportunities for attackers to potentially execute arbitrary code on affected systems. The vulnerability affects not only Thunderbird but also extends to Firefox and Firefox ESR products, indicating a widespread impact across Mozilla's browser ecosystem.
These memory safety bugs represent a fundamental flaw in how the affected applications handle memory allocation and deallocation processes. When applications fail to properly validate memory operations, they become susceptible to buffer overflows, use-after-free conditions, and other memory corruption scenarios that can be exploited by malicious actors. The presence of memory corruption evidence suggests that these vulnerabilities could allow attackers to manipulate program execution flow, potentially leading to complete system compromise. The vulnerability's classification aligns with CWE-122, which specifically addresses buffer overflow conditions in memory management operations. Such flaws are particularly dangerous because they can be leveraged to bypass security mechanisms and execute malicious payloads with the privileges of the affected application.
The operational impact of CVE-2016-9893 extends beyond simple exploitation possibilities to encompass significant risks for organizations relying on affected software versions. Attackers who successfully exploit these vulnerabilities could gain unauthorized access to systems, potentially leading to data breaches, system compromise, or the installation of additional malware. The fact that the vulnerability affects both desktop browser applications and email clients creates multiple attack vectors, as users may encounter these exploits through web browsing activities or email attachments. Organizations running affected versions of Firefox, Firefox ESR, or Thunderbird face elevated risk of targeted attacks, particularly in environments where users interact with untrusted web content or email communications. The vulnerability's potential for arbitrary code execution places it firmly within the ATT&CK framework's execution tactics, specifically under techniques such as "Command and Scripting Interpreter" and "Exploitation for Client Execution."
Mitigation strategies for CVE-2016-9893 primarily focus on immediate software updates and patches provided by Mozilla to address the identified memory safety issues. Organizations should prioritize upgrading to patched versions of Firefox 50.1, Firefox ESR 45.6, and Thunderbird 45.6 to eliminate the vulnerability exposure. Additionally, implementing network-based security controls such as web application firewalls and content filtering systems can help reduce the risk of exploitation attempts. Security monitoring should include detection of unusual network activity or system behavior that might indicate exploitation attempts. The vulnerability's nature suggests that regular security assessments and vulnerability management processes are essential for maintaining protection against similar memory safety issues. Organizations should also consider implementing principle of least privilege access controls and application whitelisting to limit the potential impact of successful exploitation attempts, as these memory corruption vulnerabilities often require elevated privileges to fully compromise system integrity.