CVE-2026-109261 in ImageMagick
Summary
by MITRE • 10/12/2026
ImageMagick before 6.9.13-57 and 7.x before 7.1.2-32 contains a memory leak in the GIF encoder because allocated memory is not released when color quantization fails during encoding. Attackers can supply images whose GIF conversion causes quantization to fail, leaking memory with each attempt and degrading availability.
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Analysis
by VulDB Data Team • 10/12/2026
The vulnerability identified in ImageMagick versions prior to 6.9.13-57 and 7.x before 7.1.2-32 represents a significant resource management flaw within the GIF encoding subsystem. This issue stems from improper handling of memory allocation during the color quantization phase, which is a critical step in converting images into the Graphics Interchange Format. When ImageMagick processes an image for GIF output, it must reduce the number of colors to fit within the format's limitation of 256 distinct colors per frame. This process involves complex algorithms that allocate temporary buffers and data structures to manage color palettes and pixel mappings. Under normal circumstances, these resources are properly deallocated upon completion or failure. However, in this specific scenario, if the quantization algorithm encounters an error condition—such as when processing images with unusual color distributions, extreme contrast levels, or malformed metadata—the code path fails to execute the necessary cleanup routines. Consequently, memory blocks that were allocated for the failed operation remain resident in the process heap indefinitely until the application terminates.
From a technical perspective, this flaw is classified under CWE-401, which describes missing release of memory after effective usage. The root cause lies in the error handling logic within the GIF encoder module. When quantization fails, instead of returning an error code and freeing all associated pointers, the function returns early without invoking the corresponding free operations for every allocation made during that specific encoding attempt. This creates a classic resource leak pattern where each failed conversion request consumes additional system memory. The vulnerability is particularly insidious because it does not cause immediate application crashes or allow arbitrary code execution in its basic form. Instead, it operates as a stealthy drain on system resources, making it difficult to detect through standard monitoring tools that look for sudden spikes rather than gradual accumulation over time.
The operational impact of this vulnerability centers primarily on the availability aspect of the CIA triad. An attacker can exploit this flaw by submitting a series of crafted images designed to trigger quantization failures during GIF conversion requests. Since many web applications and image processing services use ImageMagick as their backend engine for handling user-uploaded content, an adversary does not need direct access to the server but only needs to interact with the public-facing API or upload functionality. By repeatedly sending these malicious payloads, the attacker can induce a denial of service condition known as a resource exhaustion attack. Over time, the continuous leakage of memory will consume all available RAM on the host system. This leads to severe performance degradation for legitimate users, potential swapping activity that further slows down the server, and eventually causes the operating system or container environment to kill the ImageMagick process due to out-of-memory conditions. In cloud environments, this could lead to increased costs if auto-scaling triggers are activated by high memory usage, or complete service unavailability if resources are capped.
This vulnerability aligns with several entries in the MITRE ATT&CK framework, specifically relating to resource hijacking and denial of service techniques. It exemplifies how attackers can leverage application-level logic flaws to disrupt services without needing sophisticated exploitation tools. The attack vector is typically remote via network communication where image files are uploaded or processed through web interfaces. Defense-in-depth strategies should be employed to mitigate the risk associated with this flaw. Organizations running affected versions must upgrade ImageMagick to version 6.9.13-57 or later, and for the major branch 7.x, they must update to version 7.1.2-32 or higher where these memory management issues have been rectified by ensuring that all allocated resources are freed regardless of whether quantization succeeds or fails.
In addition to patching, administrators should implement strict input validation and rate limiting on image processing endpoints to limit the frequency at which conversion requests can be made. This reduces the window of opportunity for an attacker to exhaust system memory before the leak is detected. Furthermore, deploying resource monitoring alerts that track memory consumption trends over time rather than just instantaneous peaks can help identify such gradual leaks early. It is also advisable to run ImageMagick processes in isolated environments with strict memory limits using containerization or cgroups, so that even if an attack succeeds, it does not compromise the entire host system but merely restarts within its allocated quota. Regular security audits and static code analysis focused on resource management patterns can further prevent similar vulnerabilities from being introduced into custom integrations of ImageMagick in future development cycles.