NULL Pointer Dereference in ImageMagick Causes Remote DoS

Executive Summary

CVE-2026-25798 is a moderate severity vulnerability in ImageMagick, a software used for editing and manipulating digital images. The vulnerability is a NULL pointer dereference in the function ClonePixelCacheRepository, which can be triggered by processing a specially crafted image file.

This flaw allows a remote attacker to crash any application linked against ImageMagick without requiring any privileges or user interaction, resulting in a denial of service.

The issue occurs in the MagickCore/cache.c source file, specifically around line 753 in ClonePixelCacheRepository, and is related to other functions like OpenPixelCache, GetImagePixelCache, SyncImagePixelCache, and SetImageExtent.

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Impact Analysis

This vulnerability can impact you by allowing a remote attacker to cause a denial of service (DoS) on any application that uses ImageMagick by supplying a crafted image file.

The attacker does not need any privileges or user interaction to exploit this flaw, making it easier to trigger a crash and disrupt availability of the affected application.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability can be detected by testing whether applications linked against vulnerable versions of ImageMagick crash when processing specially crafted image files that trigger a NULL pointer dereference in the ClonePixelCacheRepository function.'}, {'type': 'paragraph', 'content': 'One practical approach is to use a crafted image file known to exploit this flaw and observe if the application crashes or generates an AddressSanitizer report indicating a NULL pointer dereference.'}, {'type': 'paragraph', 'content': "Specific commands are not provided in the available resources, but generally, you can test ImageMagick command-line tools (like 'magick' or 'convert') by attempting to process the crafted image file and monitoring for crashes or error messages."}] [1]

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Mitigation Strategies

The immediate mitigation step is to upgrade ImageMagick to a patched version, specifically version 7.1.2-15 or later, or 6.9.13-40 or later, where this NULL pointer dereference vulnerability has been fixed.

Until the upgrade can be applied, avoid processing untrusted or specially crafted image files that could trigger the vulnerability and cause denial of service.

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