CVE-2016-6207 in GD Graphics Library
Summary
by MITRE
Integer overflow in the _gdContributionsAlloc function in gd_interpolation.c in GD Graphics Library (aka libgd) before 2.2.3 allows remote attackers to cause a denial of service (out-of-bounds memory write or memory consumption) via unspecified vectors.
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Analysis
by VulDB Data Team • 09/13/2022
The CVE-2016-6207 vulnerability represents a critical integer overflow flaw within the GD Graphics Library, specifically within the _gdContributionsAlloc function located in gd_interpolation.c. This library serves as a fundamental graphics manipulation tool used across numerous applications and web platforms for image processing tasks. The vulnerability exists in versions prior to 2.2.3, making it a significant concern for systems that rely on this graphics library for handling image operations. The integer overflow occurs during memory allocation processes when the library attempts to calculate memory requirements for interpolation operations, creating a scenario where malicious input can trigger unexpected behavior.
The technical exploitation of this vulnerability stems from improper handling of integer arithmetic within the _gdContributionsAlloc function. When processing certain image interpolation requests, the function performs calculations that can exceed the maximum value representable by the integer data type, causing an overflow condition. This overflow results in incorrect memory allocation decisions where the system either attempts to write beyond valid memory boundaries or allocates insufficient memory for legitimate operations. The vulnerability's impact manifests as either out-of-bounds memory writes that can corrupt adjacent memory regions or excessive memory consumption that leads to system resource exhaustion and potential denial of service conditions.
From an operational perspective, this vulnerability presents a severe risk to web applications and services that utilize the GD Graphics Library for image processing tasks. Remote attackers can leverage this flaw by submitting specially crafted image data that triggers the vulnerable integer overflow during interpolation calculations. The resulting denial of service conditions can affect web servers, content management systems, image processing pipelines, and any application that depends on libgd for graphic rendering. The vulnerability's remote exploitability means that attackers do not require local system access or special privileges to cause disruption, making it particularly dangerous in multi-tenant environments or public-facing applications.
The vulnerability aligns with CWE-190, which categorizes integer overflow conditions, and demonstrates characteristics consistent with the ATT&CK technique T1499.004 for network denial of service attacks. Organizations using affected versions of libgd should prioritize immediate patching to address this vulnerability, as the integer overflow can be exploited to cause system instability or complete service interruption. Mitigation strategies include upgrading to libgd version 2.2.3 or later, implementing input validation for image processing operations, and deploying network monitoring to detect unusual memory consumption patterns. Additionally, system administrators should consider implementing application-level restrictions on image upload sizes and types to minimize exposure to this class of vulnerability while awaiting full patch deployment across all affected systems.