CVE-2026-25799: ImageMagick DoS Vulnerability

CVE-2026-25799 Overview

CVE-2026-25799 is a denial-of-service vulnerability in ImageMagick, a widely-used open-source software suite for editing and manipulating digital images. A logic error in YUV sampling factor validation allows an invalid sampling factor to bypass checks and trigger a division-by-zero during image loading, resulting in a reliable denial-of-service condition.

Critical Impact

Attackers can craft malicious image files that crash ImageMagick processes, causing service disruption for applications that rely on ImageMagick for image processing.

Affected Products

• ImageMagick versions prior to 7.1.2-15
• ImageMagick versions prior to 6.9.13-40

Discovery Timeline

• 2026-02-24 - CVE-2026-25799 published to NVD
• 2026-02-24 - Last updated in NVD database

Technical Details for CVE-2026-25799

Vulnerability Analysis

This vulnerability is classified as CWE-369 (Divide By Zero). The flaw exists in the YUV sampling factor validation logic within ImageMagick's image processing routines. When processing specially crafted image files, the application fails to properly validate sampling factors before using them in arithmetic operations. An invalid sampling factor can bypass the existing validation checks, allowing a zero value to be used as a divisor. This results in a division-by-zero exception that immediately terminates the ImageMagick process.

The vulnerability is particularly concerning for web applications and services that accept user-uploaded images and process them through ImageMagick, as a single malicious image can crash the processing service.

Root Cause

The root cause is a logic error in the validation routine for YUV sampling factors. The existing validation checks contain a flaw that allows certain invalid values to pass through without being caught. When these values are subsequently used in division operations during image loading and processing, the application crashes with a floating-point exception.

Attack Vector

The attack vector is network-based, requiring no authentication or user interaction. An attacker can exploit this vulnerability by uploading or submitting a maliciously crafted image file to any application that uses affected versions of ImageMagick for image processing. The crafted image contains invalid YUV sampling factor values that bypass validation and trigger the division-by-zero condition when ImageMagick attempts to load the image.

Common attack scenarios include:

• Uploading malicious images to web applications with image processing capabilities
• Sending crafted images via email to systems with automatic image preview/thumbnail generation
• Hosting malicious images on websites visited by applications that fetch and process remote images

Detection Methods for CVE-2026-25799

Indicators of Compromise

• Unexpected ImageMagick process crashes with floating-point exception (SIGFPE) signals
• Application logs showing division-by-zero errors during image processing operations
• Repeated crashes when processing images from specific sources or users
• Core dumps indicating crashes within YUV image handling code paths

Detection Strategies

• Monitor system logs for ImageMagick processes terminating with signal 8 (SIGFPE)
• Implement file integrity monitoring on ImageMagick configuration and binary files
• Deploy network-based detection rules to identify potentially malicious image uploads
• Use application-level logging to track failed image processing operations

Monitoring Recommendations

• Enable detailed logging for all image processing operations in applications using ImageMagick
• Configure process monitoring to alert on repeated ImageMagick crashes
• Implement rate limiting and anomaly detection for image upload endpoints
• Monitor resource utilization patterns that may indicate exploitation attempts

How to Mitigate CVE-2026-25799

Immediate Actions Required

• Upgrade ImageMagick to version 7.1.2-15 or later for the 7.x branch
• Upgrade ImageMagick to version 6.9.13-40 or later for the 6.x branch
• Implement input validation and file type verification before processing user-supplied images
• Consider sandboxing ImageMagick processes to limit the impact of crashes

Patch Information

ImageMagick has released patches in versions 7.1.2-15 and 6.9.13-40 that address this vulnerability. The fix corrects the logic error in YUV sampling factor validation to properly reject invalid values before they can trigger division-by-zero conditions. For detailed information about the patch, refer to the GitHub Security Advisory.

Workarounds

• Disable YUV image format processing if not required using ImageMagick's policy configuration
• Implement pre-processing validation to reject suspicious image files before they reach ImageMagick
• Run ImageMagick in isolated containers or sandboxes to contain crashes
• Configure process supervision to automatically restart crashed ImageMagick services

# Example policy.xml configuration to restrict image processing
# Add to /etc/ImageMagick-7/policy.xml or equivalent location
# Restrict coder rights for potentially vulnerable formats
<policy domain="coder" rights="none" pattern="YUV" />