CVE-2016-5297 in Firefox
Summary
by MITRE
An error in argument length checking in JavaScript, leading to potential integer overflows or other bounds checking issues. This vulnerability affects Thunderbird < 45.5, Firefox ESR < 45.5, and Firefox < 50.
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Analysis
by VulDB Data Team • 11/25/2025
The vulnerability identified as CVE-2016-5297 represents a critical flaw in JavaScript engine implementations within Mozilla Firefox and Thunderbird browsers. This issue stems from inadequate validation of argument lengths during JavaScript execution, creating potential pathways for integer overflow conditions and bounds checking failures that could be exploited by malicious actors. The vulnerability specifically impacts versions prior to Firefox 50 and Firefox ESR 45.5, as well as Thunderbird versions below 45.5, making it a widespread concern across multiple Mozilla products. The flaw resides in the JavaScript engine's handling of function arguments where insufficient boundary checks allow for improper memory access patterns that could lead to arbitrary code execution.
The technical nature of this vulnerability aligns with CWE-190, which describes integer overflow conditions that occur when a program attempts to perform arithmetic operations on integer values that exceed their maximum representable value. In this case, the JavaScript engine's argument length validation mechanisms fail to properly verify input parameters, allowing attackers to craft malicious JavaScript code that manipulates argument counts in ways that bypass normal safety checks. The flaw operates at the intersection of memory management and input validation, where the JavaScript engine's internal representation of function arguments becomes vulnerable to manipulation through crafted input sequences. This creates opportunities for attackers to exploit memory corruption vulnerabilities that could lead to complete system compromise.
The operational impact of CVE-2016-5297 extends beyond simple denial of service conditions, as it provides potential attackers with means to execute arbitrary code within the context of the browser application. When exploited successfully, this vulnerability could enable remote code execution capabilities that allow attackers to install malware, steal sensitive data, or take complete control of affected systems. The vulnerability's presence in both Firefox and Thunderbird makes it particularly dangerous as it affects not only web browsing but also email client functionality, expanding the potential attack surface significantly. Security researchers have categorized this issue as high-risk due to its potential for remote exploitation and the widespread use of affected browser versions across enterprise and consumer environments.
Mitigation strategies for CVE-2016-5297 primarily focus on immediate software updates and patches provided by Mozilla to address the underlying JavaScript engine flaw. Organizations should prioritize updating all affected systems to versions 50 or later for Firefox, 45.5 or later for Firefox ESR, and 45.5 or later for Thunderbird to eliminate exposure to this vulnerability. Additional defensive measures include implementing strict content security policies, enabling sandboxing features where available, and deploying web application firewalls that can detect and block suspicious JavaScript patterns. Network administrators should also consider implementing browser hardening techniques such as disabling unnecessary JavaScript features, restricting access to potentially malicious websites, and monitoring for anomalous behavior that might indicate exploitation attempts. The vulnerability's classification under ATT&CK technique T1059.007 for JavaScript/Visual Basic Scripting demonstrates its relevance to automated exploitation frameworks and underscores the importance of comprehensive security measures beyond simple patch management.