CVE-2011-2371 in Firefox
Summary
by MITRE
Integer overflow in the Array.reduceRight method in Mozilla Firefox before 3.6.18 and 4.x through 4.0.1, Thunderbird before 3.1.11, and SeaMonkey through 2.0.14 allows remote attackers to execute arbitrary code via vectors involving a long JavaScript Array object.
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Analysis
by VulDB Data Team • 06/08/2025
The vulnerability identified as CVE-2011-2371 represents a critical integer overflow flaw within the JavaScript engine of Mozilla Firefox and related applications. This issue affects versions prior to Firefox 3.6.18 and 4.x through 4.0.1, as well as Thunderbird before 3.1.11 and SeaMonkey through 2.0.14. The vulnerability specifically targets the Array.reduceRight method, which is a fundamental JavaScript array manipulation function used extensively in web applications. The integer overflow occurs during the processing of large JavaScript array objects, creating a condition where the system fails to properly handle array indices that exceed the maximum representable integer value, leading to unpredictable behavior in memory management.
The technical exploitation of this vulnerability involves crafting malicious JavaScript code that creates extremely long array objects, typically through the manipulation of array length properties or iterative array construction techniques. When the Array.reduceRight method processes these oversized arrays, the integer overflow causes the array indexing calculations to wrap around to negative values or extremely large positive values, resulting in memory corruption. This memory corruption can be leveraged by attackers to overwrite critical memory locations, potentially allowing for arbitrary code execution. The vulnerability falls under CWE-190, Integer Overflow or Wraparound, which is a well-documented class of vulnerabilities that occurs when an integer value exceeds its maximum representable value and wraps around to a smaller value. The attack vector requires the victim to execute JavaScript code within a vulnerable browser environment, typically through malicious web pages or email attachments.
The operational impact of CVE-2011-2371 extends beyond simple code execution, as it represents a significant threat to web browser security and user data integrity. The vulnerability allows attackers to bypass security mechanisms that rely on proper array handling, potentially enabling them to execute malicious payloads with the privileges of the browser process. This could lead to complete system compromise, data theft, or the installation of persistent malware. The attack surface is particularly concerning given that the vulnerability affects multiple Mozilla products, including the widely used Firefox browser, Thunderbird email client, and SeaMonkey suite, making it a prime target for mass exploitation campaigns. The vulnerability demonstrates how seemingly innocuous JavaScript array operations can become dangerous when integer overflow conditions are not properly handled, highlighting the importance of robust input validation and memory safety in web browser implementations.
Mitigation strategies for this vulnerability primarily involve immediate software updates and patches from Mozilla, as the most effective solution requires upgrading to versions that contain the necessary fixes. Organizations should implement comprehensive patch management procedures to ensure all affected systems are updated promptly, particularly given the remote execution capabilities of this vulnerability. Browser security configurations should be reviewed to disable unnecessary JavaScript functionality when possible, and security software should be configured to monitor for suspicious JavaScript behavior patterns. The vulnerability also underscores the importance of following secure coding practices, particularly in handling array operations and integer calculations, as outlined in various security frameworks and standards. Additionally, network-based intrusion detection systems should be configured to identify and block known malicious JavaScript patterns associated with this vulnerability, and user education programs should emphasize the importance of avoiding untrusted websites and email attachments that could contain exploit code. The ATT&CK framework categorizes this vulnerability under the T1059.007 technique for JavaScript execution, and the T1078.004 technique for legitimate credentials usage, as attackers may leverage this vulnerability to establish persistent access to compromised systems.