CVE-2026-30929: ImageMagick Buffer Overflow Vulnerability

CVE-2026-30929 Overview

CVE-2026-30929 is a stack buffer overflow vulnerability in ImageMagick, the widely-used open-source software for editing and manipulating digital images. The vulnerability exists in the MagnifyImage function, which uses a fixed-size stack buffer. When processing a specially crafted image, an attacker can overflow this buffer and corrupt the stack, potentially leading to arbitrary code execution or denial of service.

Critical Impact

This stack buffer overflow vulnerability allows attackers to corrupt stack memory through maliciously crafted images, potentially enabling code execution or application crashes on systems processing untrusted image files.

Affected Products

• ImageMagick versions prior to 7.1.2-16
• ImageMagick versions prior to 6.9.13-41

Discovery Timeline

• 2026-03-10 - CVE CVE-2026-30929 published to NVD
• 2026-03-11 - Last updated in NVD database

Technical Details for CVE-2026-30929

Vulnerability Analysis

This vulnerability is classified as CWE-121 (Stack-based Buffer Overflow). The flaw resides in the MagnifyImage function within ImageMagick's image processing pipeline. The function allocates a fixed-size buffer on the stack to handle image magnification operations. When processing images with specific characteristics, the function fails to properly validate input bounds before writing data to this stack buffer.

The local attack vector means an attacker must have the ability to provide a malicious image file to a vulnerable system. This could occur through various scenarios including web applications that process user-uploaded images, email systems that generate image thumbnails, or document processing systems that extract and manipulate embedded images.

Root Cause

The root cause of CVE-2026-30929 is improper bounds checking in the MagnifyImage function. The function uses a statically allocated stack buffer with a predetermined size, but fails to validate that incoming image data will fit within these bounds. When image dimensions or pixel data exceed the expected parameters, the function continues writing beyond the buffer boundary, corrupting adjacent stack memory including potentially the return address and saved registers.

Attack Vector

The attack requires local access to provide a malicious image file. An attacker must craft a specially designed image that triggers the overflow condition when processed by the MagnifyImage function. The image would contain specific dimensions or pixel arrangements that cause the function to write more data than the stack buffer can accommodate.

The vulnerability affects systems where ImageMagick processes untrusted images, including web servers handling user uploads, content management systems, document converters, and any application integrating ImageMagick libraries for image manipulation.

The exploitation mechanism involves providing a crafted image file that triggers the MagnifyImage code path with data exceeding the fixed stack buffer size. For detailed technical information, refer to the GitHub Security Advisory.

Detection Methods for CVE-2026-30929

Indicators of Compromise

• Application crashes or segmentation faults when processing image files through ImageMagick
• Unexpected memory corruption errors in logs from ImageMagick processes
• Unusual image files with abnormal dimensions or metadata in upload directories

Detection Strategies

• Monitor ImageMagick processes for abnormal memory consumption or crashes using process monitoring tools
• Implement file integrity monitoring on systems where ImageMagick is installed to detect unauthorized modifications
• Deploy endpoint detection solutions capable of identifying stack-based buffer overflow exploitation attempts
• Review application logs for ImageMagick error messages indicating malformed image processing

Monitoring Recommendations

• Enable verbose logging for ImageMagick operations to capture processing errors
• Configure crash dump collection for ImageMagick processes to analyze potential exploitation attempts
• Monitor file upload directories for suspicious image files with unusual characteristics
• Implement alerting on repeated ImageMagick process restarts which may indicate ongoing exploitation attempts

How to Mitigate CVE-2026-30929

Immediate Actions Required

• Update ImageMagick to version 7.1.2-16 or later for the 7.x branch
• Update ImageMagick to version 6.9.13-41 or later for the 6.x branch
• Audit systems to identify all instances of ImageMagick installations requiring updates
• Implement input validation for image files before processing with ImageMagick

Patch Information

ImageMagick has released patched versions that address this stack buffer overflow vulnerability. Organizations should upgrade to ImageMagick 7.1.2-16 or 6.9.13-41 depending on their deployment branch. The patches implement proper bounds checking in the MagnifyImage function to prevent buffer overflow conditions.

For detailed patch information and release notes, see the GitHub Security Advisory.

Workarounds

• Implement ImageMagick policy restrictions to disable the Magnify operation if not required
• Process untrusted images in sandboxed environments with limited privileges
• Use ImageMagick's resource limits to constrain memory and processing operations
• Consider alternative image processing libraries for handling untrusted content until patches can be applied

# ImageMagick policy.xml configuration to restrict operations
# Add to /etc/ImageMagick-7/policy.xml or equivalent location
# Disable potentially dangerous operations for untrusted content
# <policy domain="delegate" rights="none" pattern="*" />
# <policy domain="resource" name="memory" value="256MiB" />
# <policy domain="resource" name="width" value="8KP" />
# <policy domain="resource" name="height" value="8KP" />