CVE-2016-6214 in GD Graphics Library
Summary
by MITRE
gd_tga.c in the GD Graphics Library (aka libgd) before 2.2.3 allows remote attackers to cause a denial of service (out-of-bounds read) via a crafted TGA file.
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Analysis
by VulDB Data Team • 09/13/2022
The GD Graphics Library represents a widely-used open-source graphics library that provides fundamental image manipulation capabilities for numerous applications and web servers. This particular vulnerability exists within the gd_tga.c module responsible for handling Targa image format processing. The flaw manifests as an out-of-bounds read condition that occurs when parsing specially crafted TGA files, creating a scenario where memory access occurs beyond the allocated buffer boundaries. This vulnerability falls under the category of memory safety issues and specifically aligns with CWE-125, which describes out-of-bounds read conditions that can lead to unpredictable behavior and system instability. The vulnerability affects versions prior to 2.2.3, indicating that the developers identified and addressed this specific memory access pattern in their subsequent releases.
The technical execution of this vulnerability requires an attacker to prepare a malicious TGA file that triggers the out-of-bounds read during the image parsing process. When the GD library attempts to process such a crafted file, the parser fails to properly validate the TGA file structure and header information, leading to memory access violations. The out-of-bounds read can potentially expose sensitive data from adjacent memory locations or cause the application to crash entirely, resulting in denial of service conditions that can affect any system utilizing the vulnerable library. This type of vulnerability represents a classic example of improper input validation and insufficient bounds checking, which are common attack vectors in graphics processing libraries where complex file format parsing occurs.
The operational impact of CVE-2016-6214 extends beyond simple denial of service to potentially compromise system stability and availability. Applications that rely on libgd for image processing, including web servers, content management systems, and image manipulation tools, become vulnerable to remote exploitation when they accept user-uploaded TGA files or process external image sources. The vulnerability can be exploited through various attack vectors including web-based file uploads, image processing pipelines, and content delivery networks that utilize the affected library. From an attacker's perspective, this represents a low-effort, high-impact method for causing service disruption, as the malicious TGA file can be crafted with minimal complexity to trigger the memory access violation. The vulnerability also aligns with ATT&CK technique T1499.004, which covers network denial of service attacks through resource exhaustion or memory corruption.
Mitigation strategies for this vulnerability require immediate patching of affected systems to upgrade to libgd version 2.2.3 or later, which contains the necessary bounds checking fixes. System administrators should also implement input validation measures that restrict TGA file uploads and perform additional sanitization of image files before processing. Network-level protections such as intrusion detection systems can be configured to detect and block suspicious TGA file patterns. Additionally, organizations should conduct comprehensive vulnerability assessments to identify all systems using the vulnerable library and ensure proper patch management procedures are in place. The fix implemented by the libgd development team involved strengthening the TGA file parsing logic to properly validate header structures and memory access boundaries, preventing the out-of-bounds read conditions that previously allowed attackers to exploit the library.