CVE-2016-9317 in GD Graphics Library
Summary
by MITRE
The gdImageCreate function in the GD Graphics Library (aka libgd) before 2.2.4 allows remote attackers to cause a denial of service (system hang) via an oversized image.
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Analysis
by VulDB Data Team • 05/14/2026
The gd Graphics Library represents a widely deployed software component used for creating and manipulating raster graphics in numerous applications across different platforms. This library serves as a foundational element in web applications, content management systems, and server-side image processing tools. The vulnerability under analysis stems from the gdImageCreate function within libgd versions prior to 2.2.4, which fails to properly validate input parameters when handling image data. This flaw manifests as a denial of service condition that can cause system hang, effectively rendering the affected applications unavailable to legitimate users.
The technical implementation of this vulnerability occurs when the gdImageCreate function processes an image with dimensions that exceed acceptable bounds. The function lacks proper boundary checking mechanisms that would normally prevent processing of images with excessively large width or height values. When an attacker submits an oversized image, the library enters into an infinite loop or consumes excessive system resources during the image creation process, leading to complete system unresponsiveness. This behavior aligns with CWE-129, which addresses improper validation of array indices and other input validation issues that can lead to resource exhaustion. The vulnerability specifically exploits the library's failure to implement reasonable limits on image dimensions, creating a condition where legitimate image processing operations become impossible due to resource consumption.
The operational impact of CVE-2016-9317 extends beyond simple denial of service, as it can affect entire web applications and services that rely on libgd for image handling. Attackers can exploit this vulnerability by uploading or submitting specially crafted image files that trigger the problematic code path in the GD Graphics Library. The system hang condition typically affects the web server process or application instance handling the image request, potentially causing cascading failures in service availability. This vulnerability demonstrates a classic resource exhaustion attack pattern that can be executed remotely without requiring authentication or specialized privileges. The impact is particularly severe in high-traffic environments where multiple simultaneous requests could cause widespread service disruption.
Mitigation strategies for this vulnerability require immediate patching of affected libgd installations to version 2.2.4 or later, which contains the necessary input validation fixes. Organizations should implement proper image size validation at application level before passing files to the GD library, establishing reasonable limits for image dimensions to prevent exploitation. Network-level protections such as rate limiting and request filtering can help reduce the impact of exploitation attempts. Additionally, implementing proper monitoring and alerting for system resource consumption can help detect exploitation attempts before they cause complete service disruption. From an ATT&CK framework perspective, this vulnerability maps to T1499.004, which covers network denial of service attacks, and T1071.004, covering application layer protocol use for command and control. Organizations should also consider implementing web application firewalls and content filtering systems to prevent malicious image uploads from reaching vulnerable applications. The remediation process should include thorough testing of patched libraries to ensure compatibility with existing applications while maintaining security posture against similar vulnerabilities in other components of the image processing pipeline.