CVE-2026-62946: 
C# vulnerability analysis and mitigation

CVE-2026-62946 is an integer overflow vulnerability in ImageMagick's JNX file decoder that causes a heap buffer over-write when processing extremely large JNX files on 32-bit platforms. It affects ImageMagick versions prior to 6.9.13-52 and 7.1.2-27, as well as Magick.NET NuGet packages prior to version 14.15.0. The vulnerability was published by the ImageMagick project on July 15, 2026, with the GitHub Advisory Database entry updated on July 24, 2026. It carries a CVSS v3.1 base score of 5.1 (Moderate) per the GitHub advisory, though NVD assigns it 4.7 (Medium) (GitHub Advisory, Red Hat Bugzilla).

The root cause is an integer overflow or wraparound (CWE-190) in the JNX image decoder. On 32-bit platforms, when ImageMagick processes a specially crafted, extremely large JNX file, an arithmetic calculation overflows the 32-bit integer boundary, resulting in an undersized heap buffer allocation. Subsequent writes to this buffer exceed its bounds, constituting a heap buffer over-write. Exploitation requires the attacker to supply a malicious JNX file to a vulnerable 32-bit ImageMagick build; the vulnerability is not present on 64-bit platforms where larger integer types prevent the overflow condition (GitHub Advisory, GitHub Advisory).

Successful exploitation results in a denial of service (DoS) through application crash or memory corruption on affected 32-bit ImageMagick deployments. The CVSS assessment indicates high availability impact with no confidentiality or integrity impact, meaning attackers cannot directly read or modify data through this vulnerability. The scope is limited to the affected process and does not extend to other system components, and there is no known potential for lateral movement or sensitive data exposure (GitHub Advisory, Red Hat Bugzilla).

No public proof-of-concept exploit code or in-the-wild exploitation has been reported for CVE-2026-62946. The EPSS score is approximately 0.123% (2nd percentile), indicating a low probability of exploitation in the near term. The NVD SSVC assessment classifies exploitation as "none" and the attack as non-automatable. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Exploitation is constrained to 32-bit platform builds and requires high attack complexity, further limiting practical risk (GitHub Advisory).

1. Identify target: Locate a system running a 32-bit build of ImageMagick (versions prior to 6.9.13-52 or 7.1.2-27) or Magick.NET prior to 14.15.0 that processes user-supplied image files.
2. Craft malicious JNX file: Create an extremely large or specially structured JNX (Garmin navigation image) file designed to trigger an integer overflow in the JNX decoder's size calculation logic on 32-bit platforms.
3. Deliver the file: Submit the crafted JNX file to the target application — for example, via a web upload form, API endpoint, or any service that invokes ImageMagick for image processing.
4. Trigger the overflow: When ImageMagick processes the file, the 32-bit integer overflow occurs during buffer size calculation, resulting in an undersized heap allocation followed by an out-of-bounds write.
5. Achieve denial of service: The heap corruption causes the ImageMagick process to crash, resulting in a denial of service for the affected application or service (GitHub Advisory).

• Logs: Application or web server logs showing repeated submission of large .jnx files or files with JNX MIME types; ImageMagick process crash logs or core dump files generated during image processing.
• Process: Unexpected termination or crash of ImageMagick worker processes (convert, magick, or application processes invoking libMagickCore) when handling JNX files.
• File System: Presence of unusually large JNX files in upload directories or temporary processing directories; core dump files (e.g., core, core.<pid>) in the working directory of the ImageMagick process.

ImageMagick has released patched versions 6.9.13-52 and 7.1.2-27 that resolve this vulnerability; users should upgrade to these versions or later. For Magick.NET users, upgrading to version 14.15.0 or later addresses the issue. SUSE and openSUSE have issued security updates (SUSE-SU-2026:3414-1) for their distributions. As a workaround where upgrading is not immediately possible, administrators can restrict or disable processing of JNX files, or ensure only 64-bit builds of ImageMagick are deployed, as the vulnerability is specific to 32-bit platforms (GitHub Advisory, SUSE Advisory).

The vulnerability was credited to reporter kongzhenhit-code and disclosed responsibly through GitHub's security advisory process. Red Hat tracked the issue via Bugzilla (Bug 2508878) and classified it as medium severity. SUSE and openSUSE promptly issued security update announcements. No significant social media discussion or notable researcher commentary beyond standard advisory coverage has been observed (Red Hat Bugzilla, SUSE Advisory).