CVE-2026-23952

NULL pointer dereference in MSL (Magick Scripting Language) parser when processing <comment> tag before any image is loaded.

Version

• ImageMagick 7.x (tested on current main branch)
• Commit: HEAD

Steps to Reproduce

Method 1: Using ImageMagick directly

magick MSL:poc.msl out.png

Method 2: Using OSS-Fuzz reproduce

python3 infra/helper.py build_fuzzers imagemagick
python3 infra/helper.py reproduce imagemagick msl_fuzzer poc.msl

Or run the fuzzer directly:

./msl_fuzzer poc.msl

Expected Behavior

ImageMagick should handle the malformed MSL gracefully and return an error message.

Actual Behavior

convert: MagickCore/property.c:297: MagickBooleanType DeleteImageProperty(Image *, const char *): Assertion `image != (Image *) NULL' failed.
Aborted

Root Cause Analysis

In coders/msl.c:7091, MSLEndElement() calls DeleteImageProperty() on msl_info->image[n] when handling the </comment> end tag without checking if the image is NULL:

if (LocaleCompare((const char *) tag,"comment") == 0 )
  {
    (void) DeleteImageProperty(msl_info->image[n],"comment");  // No NULL check
    ...
  }

When <comment> appears before any <read> operation, msl_info->image[n] is NULL, causing the assertion failure in DeleteImageProperty() at property.c:297.

Fuzzer

This issue was discovered using a custom MSL fuzzer:

#include <cstdint>
#include <Magick++/Blob.h>
#include <Magick++/Image.h>
#include "utils.cc"

extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size)
{
  if (IsInvalidSize(Size))
    return(0);
  try
  {
    const Magick::Blob blob(Data, Size);
    Magick::Image image;
    image.magick("MSL");
    image.fileName("MSL:");
    image.read(blob);
  }
  catch (Magick::Exception)
  {
  }
  return(0);
}

This issue was found by Team FuzzingBrain @ Texas A&M University

• DoS: Crash via assertion failure (debug builds) or NULL pointer dereference (release builds)
• Affected: Any application using ImageMagick to process user-supplied MSL files

The application dereferences a null pointer, causing a crash. Typical impact: denial of service via crash.

CVE-2026-23952 has a CVSS score of 6.5 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (14.10.2); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-23952? CVE-2026-23952 is a medium-severity null pointer dereference vulnerability in Magick.NET-Q8-x64 (nuget), affecting versions < 14.10.2. It is fixed in 14.10.2. The application dereferences a null pointer, causing a crash.
2. How severe is CVE-2026-23952? CVE-2026-23952 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2026-23952?
   • Magick.NET-Q8-x64 (nuget) (versions < 14.10.2)
   • Magick.NET-Q8-arm64 (nuget) (versions < 14.10.2)
   • Magick.NET-Q8-x86 (nuget) (versions < 14.10.2)
   • Magick.NET-Q8-OpenMP-x64 (nuget) (versions < 14.10.2)
   • Magick.NET-Q8-OpenMP-arm64 (nuget) (versions < 14.10.2)
   • Magick.NET-Q16-x64 (nuget) (versions < 14.10.2)
   • Magick.NET-Q16-arm64 (nuget) (versions < 14.10.2)
   • Magick.NET-Q16-x86 (nuget) (versions < 14.10.2)
   • Magick.NET-Q16-OpenMP-x64 (nuget) (versions < 14.10.2)
   • Magick.NET-Q16-OpenMP-arm64 (nuget) (versions < 14.10.2)
   • Magick.NET-Q16-OpenMP-x86 (nuget) (versions < 14.10.2)
   • Magick.NET-Q16-HDRI-x64 (nuget) (versions < 14.10.2)
   • Magick.NET-Q16-HDRI-arm64 (nuget) (versions < 14.10.2)
   • Magick.NET-Q16-HDRI-x86 (nuget) (versions < 14.10.2)
   • Magick.NET-Q16-HDRI-OpenMP-x64 (nuget) (versions < 14.10.2)
   • Magick.NET-Q16-HDRI-OpenMP-arm64 (nuget) (versions < 14.10.2)
   • Magick.NET-Q8-AnyCPU (nuget) (versions < 14.10.2)
   • Magick.NET-Q16-AnyCPU (nuget) (versions < 14.10.2)
   • Magick.NET-Q16-HDRI-AnyCPU (nuget) (versions < 14.10.2)
4. Is there a fix for CVE-2026-23952? Yes. CVE-2026-23952 is fixed in 14.10.2. Upgrade to this version or later.
5. Is CVE-2026-23952 exploitable, and should I be worried? Whether CVE-2026-23952 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-23952 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-23952?
   • Upgrade Magick.NET-Q8-x64 to 14.10.2 or later
   • Upgrade Magick.NET-Q8-arm64 to 14.10.2 or later
   • Upgrade Magick.NET-Q8-x86 to 14.10.2 or later
   • Upgrade Magick.NET-Q8-OpenMP-x64 to 14.10.2 or later
   • Upgrade Magick.NET-Q8-OpenMP-arm64 to 14.10.2 or later
   • Upgrade Magick.NET-Q16-x64 to 14.10.2 or later
   • Upgrade Magick.NET-Q16-arm64 to 14.10.2 or later
   • Upgrade Magick.NET-Q16-x86 to 14.10.2 or later
   • Upgrade Magick.NET-Q16-OpenMP-x64 to 14.10.2 or later
   • Upgrade Magick.NET-Q16-OpenMP-arm64 to 14.10.2 or later
   • Upgrade Magick.NET-Q16-OpenMP-x86 to 14.10.2 or later
   • Upgrade Magick.NET-Q16-HDRI-x64 to 14.10.2 or later
   • Upgrade Magick.NET-Q16-HDRI-arm64 to 14.10.2 or later
   • Upgrade Magick.NET-Q16-HDRI-x86 to 14.10.2 or later
   • Upgrade Magick.NET-Q16-HDRI-OpenMP-x64 to 14.10.2 or later
   • Upgrade Magick.NET-Q16-HDRI-OpenMP-arm64 to 14.10.2 or later
   • Upgrade Magick.NET-Q8-AnyCPU to 14.10.2 or later
   • Upgrade Magick.NET-Q16-AnyCPU to 14.10.2 or later
   • Upgrade Magick.NET-Q16-HDRI-AnyCPU to 14.10.2 or later