CVE-2026-30937: ImageMagick Buffer Overflow Vulnerability

CVE-2026-30937 Overview

ImageMagick, a widely-used free and open-source software suite for image editing and manipulation, contains a critical integer overflow vulnerability in its XWD (X Windows) encoder. Prior to versions 7.1.2-16 and 6.9.13-41, a 32-bit unsigned integer overflow can cause an undersized heap buffer allocation when processing extremely large images. This leads to an out-of-bounds heap write condition (CWE-122: Heap-based Buffer Overflow), potentially allowing attackers to corrupt memory and cause application crashes or other unintended behavior.

Critical Impact
An attacker who can cause ImageMagick to process a specially crafted large image file may trigger memory corruption, potentially leading to denial of service or arbitrary code execution on vulnerable systems.

Affected Products

ImageMagick versions prior to 7.1.2-16
ImageMagick versions prior to 6.9.13-41
Any application or service that processes images using vulnerable ImageMagick versions

Discovery Timeline

2026-03-10 - CVE-2026-30937 published to NVD
2026-03-11 - Last updated in NVD database

Technical Details for CVE-2026-30937

Vulnerability Analysis

This vulnerability is classified as a Heap-based Buffer Overflow (CWE-122) resulting from an Integer Overflow condition. The flaw exists in the XWD (X Window Dump) encoder component of ImageMagick.

When ImageMagick processes an extremely large image for XWD encoding, the software performs a calculation to determine the required buffer size. Due to the use of a 32-bit unsigned integer for this calculation, processing images with dimensions that result in a size value exceeding the 32-bit boundary causes the integer to wrap around to a much smaller value. This leads to the allocation of an undersized heap buffer.

Subsequently, when the encoder attempts to write the actual image data to this undersized buffer, it writes beyond the allocated memory region, resulting in an out-of-bounds heap write. This memory corruption can lead to application crashes, denial of service, or potentially arbitrary code execution if an attacker can control the overwritten memory contents.

Root Cause

The root cause is an insufficient size check during buffer allocation in the XWD encoder. The 32-bit unsigned integer used for calculating the buffer size cannot accommodate the memory requirements for extremely large images, causing an integer overflow that wraps the value to a much smaller number than required. The subsequent heap allocation uses this incorrect, undersized value, creating a buffer that is too small for the actual data being written.

Attack Vector

The attack vector is local, requiring an attacker to provide a malicious image file to a system running vulnerable ImageMagick software. This could occur through:

Direct processing of attacker-supplied image files through command-line tools like convert or identify
Web applications that use ImageMagick to process user-uploaded images
Document processing systems that extract and process embedded images
Any automated image processing pipeline that accepts external input

The vulnerability requires the target image to have extremely large dimensions to trigger the integer overflow condition in the size calculation. For more technical details, see the GitHub Security Advisory.

Detection Methods for CVE-2026-30937

Indicators of Compromise

Unexpected crashes or segmentation faults in ImageMagick processes during image conversion operations
Memory corruption errors logged by system monitoring tools when processing XWD format images
Abnormally large image files being processed by ImageMagick instances
Core dumps or crash reports from applications using ImageMagick libraries

Detection Strategies

Monitor ImageMagick processes for abnormal memory allocation patterns or crashes during XWD encoding
Implement file size and dimension validation for images before processing with ImageMagick
Use application-level logging to track image processing operations and identify suspicious activity
Deploy endpoint detection and response (EDR) solutions to identify exploitation attempts

Monitoring Recommendations

Enable detailed logging for ImageMagick operations to capture processing failures and memory errors
Set up alerts for crashes or unexpected termination of image processing services
Monitor system logs for segmentation faults in processes using ImageMagick libraries
Implement input validation to reject images with abnormally large dimensions before processing

How to Mitigate CVE-2026-30937

Immediate Actions Required

Upgrade ImageMagick to version 7.1.2-16 or later for the 7.x branch
Upgrade ImageMagick to version 6.9.13-41 or later for the 6.x branch
Restrict image processing to trusted sources until patches are applied
Implement input validation to limit image dimensions before processing

Patch Information

The vulnerability has been fixed in ImageMagick versions 7.1.2-16 and 6.9.13-41. Organizations should update to these versions or later to remediate this vulnerability. Patch details and technical information are available in the GitHub Security Advisory.

Workarounds

Implement strict image dimension limits in applications before passing files to ImageMagick
Disable XWD format processing if not required by modifying ImageMagick's policy configuration
Use containerization to isolate ImageMagick processes and limit potential damage from exploitation
Consider using alternative image processing libraries for untrusted input until patching is complete

bash

# ImageMagick policy.xml configuration to restrict XWD format
# Add to /etc/ImageMagick-7/policy.xml or /etc/ImageMagick-6/policy.xml

<policy domain="coder" rights="none" pattern="XWD" />

# Additionally, limit image dimensions to prevent oversized images
<policy domain="resource" name="width" value="16KP"/>
<policy domain="resource" name="height" value="16KP"/>