CVE-2026-53467: ImageMagick MNG Decoder Heap Information Disclosure

Technical summary

The vulnerability stems from incomplete pixel initialization in the MNG decoder routine. MNG is a PNG-like format that supports animation and multiple images. During the decoding process, the implementation allocates heap memory for pixel buffers but fails to zero or properly initialize all allocated regions before use. When the decoder processes certain MNG structures, uninitialized heap data remains in the buffer and is incorporated into the output image. This creates an information disclosure path where adjacent heap allocations—potentially containing sensitive data—become visible to an attacker who can control the MNG input. The issue is classified under CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor) and CWE-908 (Use of Uninitialized Resource). Exploitation does not require authentication and can occur over a network if ImageMagick is exposed via a web service.

Business impact

For organizations using ImageMagick in automated image processing pipelines—such as web applications that accept user uploads, thumbnail generation services, or API-based image conversion tools—this vulnerability poses a moderate but real risk. A successful exploit could leak sensitive heap memory, potentially including database credentials, session tokens, cryptographic keys, or other in-memory secrets if they happen to reside in adjacent allocations. While the exposure is limited by heap layout randomization and the need to craft specific MNG inputs, the risk is elevated if ImageMagick processes untrusted image sources. Organizations in regulated industries (finance, healthcare, government) should treat this as a priority because even limited information disclosure can violate compliance requirements.

Affected systems

ImageMagick versions prior to 6.9.13-51 (the legacy 6.9.x branch) and 7.1.2-26 (the current 7.x branch) are affected. Any system running an unpatched version of ImageMagick that processes MNG files—whether through direct command-line use, library integration, or exposure via a web or API service—is vulnerable. This includes Docker containers, cloud functions, content delivery systems, and embedded deployments. Organizations should audit all instances where ImageMagick is installed or bundled, including in third-party software or container images.

Exploitability

Exploitation requires network access to the ImageMagick service and the ability to supply a specially crafted MNG file as input. No authentication is needed, and no user interaction is required beyond processing the malicious file. The attack complexity is low: an attacker simply sends a crafted MNG to trigger the decoder. However, the practical impact is mitigated by several factors: the attacker cannot control which heap data is exposed (it depends on runtime allocation patterns), Address Space Layout Randomization (ASLR) and heap randomization reduce predictability, and the leaked data is embedded in image output, requiring the attacker to retrieve and parse the result. Despite these constraints, the vulnerability is straightforward to trigger and warrants prompt patching, especially in internet-facing or untrusted-input scenarios.

Remediation

Upgrade ImageMagick to version 6.9.13-51 or later for the legacy branch, or to version 7.1.2-26 or later for the current branch. These versions include fixes that ensure proper initialization of heap memory in the MNG decoder. If immediate patching is not feasible, consider disabling MNG format support in ImageMagick configuration, implementing strict input validation to reject MNG files, or restricting ImageMagick to trusted image sources only. For web applications, isolate ImageMagick processing in a sandboxed environment and limit what an attacker can do with leaked memory.

Patch guidance

Verify the specific version of ImageMagick in your environment using `convert -version` (or `magick -version` for ImageMagick 7). If you are running 6.9.13-50 or earlier, or 7.1.2-25 or earlier, apply the update immediately. Consult your distribution's package manager (apt, yum, brew) for availability of patched versions, or download directly from the ImageMagick official repository. Test the patched version in a staging environment to ensure compatibility with your image processing workflows before rolling out to production. Container users should rebuild or pull updated base images with the patched ImageMagick version.

Detection guidance

Monitor system logs for ImageMagick crashes or unexpected behavior when processing MNG files. Implement application logging to record all image file uploads and their formats; flag MNG files for review if they are unexpected in your workflow. If you run ImageMagick in a service, monitor for unusual heap memory access patterns or error messages from the MNG decoder. Network-level detection is difficult because the attack is silent and embedded in normal file processing; however, if you can inspect file uploads, reject or quarantine MNG files until you patch. Consider using static analysis on any custom ImageMagick scripts to identify MNG processing paths.

Why prioritize this

Although the CVSS score of 5.3 (MEDIUM) reflects limited scope and no impact on availability or integrity, the ease of exploitation (network-accessible, no auth required, low complexity) and the nature of the exposure (heap memory leaks from a widely-trusted tool) warrant prioritization. ImageMagick is frequently integrated into web services, build pipelines, and cloud functions, expanding the potential impact. The lack of exploitation complexity and the prevalence of ImageMagick in production environments justify treating this as a near-term patch target, especially if your organization processes untrusted or user-supplied images.

Risk score, explained

The CVSS 3.1 score of 5.3 reflects a network-accessible vulnerability with low attack complexity, no privileges required, and no user interaction needed—all favoring the attacker. However, the impact is limited to confidentiality (L) with no impact on integrity or availability. The attack vector is broad (network-based), but the scope is unchanged (the attacker can only extract data from the vulnerable process itself). The score appropriately captures moderate risk: not as severe as critical or high-impact flaws, but definitely meriting prompt remediation given the prevalence of ImageMagick and the simplicity of triggering the flaw.

Frequently asked questions