CVE-2014-1523 in Firefox
Summary
by MITRE
Heap-based buffer overflow in the read_u32 function in Mozilla Firefox before 29.0, Firefox ESR 24.x before 24.5, Thunderbird before 24.5, and SeaMonkey before 2.26 allows remote attackers to cause a denial of service (out-of-bounds read and application crash) via a crafted JPEG image.
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Analysis
by VulDB Data Team • 11/25/2025
The vulnerability identified as CVE-2014-1523 represents a critical heap-based buffer overflow affecting Mozilla Firefox and related applications. This flaw exists within the read_u32 function, which processes 32-bit unsigned integer values during image parsing operations. The vulnerability specifically impacts versions prior to Firefox 29.0, Firefox ESR 24.x before 24.5, Thunderbird before 24.5, and SeaMonkey before 2.26, making it a widespread issue affecting multiple Mozilla products. The flaw manifests when processing crafted JPEG images, which can trigger memory corruption through improper bounds checking during data parsing.
The technical implementation of this vulnerability stems from insufficient input validation within the JPEG image decoder component of the Mozilla application suite. When a maliciously crafted JPEG file is processed, the read_u32 function fails to properly validate the boundaries of heap-allocated memory regions, leading to an out-of-bounds read condition. This memory corruption occurs because the function attempts to read 32-bit values from memory locations that extend beyond the allocated buffer boundaries. The vulnerability is classified as a heap-based buffer overflow according to CWE-122, which specifically addresses heap memory corruption issues where insufficient bounds checking allows access beyond allocated memory regions. The flaw demonstrates characteristics consistent with CWE-787, which describes out-of-bounds write operations that can result in memory corruption.
The operational impact of CVE-2014-1523 extends beyond simple denial of service to potentially enable more sophisticated attack vectors. Remote attackers can exploit this vulnerability by delivering malicious JPEG images through various attack vectors including web browsers, email clients, or web applications that utilize Mozilla's image processing libraries. The immediate consequence is application crash and denial of service, but the underlying memory corruption could potentially be leveraged for more advanced exploitation techniques. This vulnerability aligns with ATT&CK technique T1203, which covers exploitation of software vulnerabilities for privilege escalation or persistent access. The out-of-bounds read condition creates opportunities for attackers to potentially manipulate memory contents or extract sensitive information from the application's memory space.
Mitigation strategies for CVE-2014-1523 primarily focus on immediate version upgrades to patched releases of affected Mozilla applications. System administrators should prioritize updating Firefox, Thunderbird, and SeaMonkey installations to versions 29.0, 24.5, and 2.26 respectively, which contain the necessary fixes for the buffer overflow condition. Additionally, implementing network-level protections such as content filtering and sandboxing mechanisms can provide additional defense-in-depth layers. Organizations should also consider disabling automatic image rendering in email clients and web browsers until patches are applied. The vulnerability demonstrates the importance of input validation and bounds checking in memory management operations, reinforcing principles from the OWASP Top Ten security risks that emphasize the need for proper input sanitization and memory safety practices in application development.