CVE-2025-57807: ImageMagick Buffer Overflow Vulnerability

CVE-2025-57807 Overview

CVE-2025-57807 is a critical heap-based buffer overflow vulnerability affecting ImageMagick, the widely-used open-source software for editing and manipulating digital images. The vulnerability exists in the SeekBlob() and WriteBlob() functions within MagickCore/blob.c, where improper memory extent calculations allow an attacker to write to memory locations beyond the allocated buffer.

The flaw occurs because SeekBlob() permits advancing the stream offset beyond the current end without increasing capacity, while WriteBlob() expands memory by quantum + length (amortized) instead of the correct offset + length, and then copies data to data + offset. When the offset significantly exceeds the extent, the copy operation targets memory beyond the allocation, producing a deterministic heap write on 64-bit builds.

Critical Impact

This vulnerability enables remote attackers to achieve arbitrary code execution by processing maliciously crafted image files. No special configuration, policy settings, or external delegates are required for exploitation.

Affected Products

• ImageMagick versions prior to 14.8.2
• All 64-bit builds of affected versions
• Systems processing untrusted image files through ImageMagick

Discovery Timeline

• 2025-09-05 - CVE-2025-57807 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2025-57807

Vulnerability Analysis

This heap-based buffer overflow (CWE-122) stems from a fundamental miscalculation in how ImageMagick manages blob memory extents. The vulnerability is particularly dangerous because it produces deterministic heap writes without requiring any 2⁶⁴ arithmetic wrap conditions.

The core issue lies in the interaction between two functions in the blob handling code. When SeekBlob() positions the stream offset past the current data extent, the subsequent call to WriteBlob() incorrectly calculates the required memory expansion. Instead of allocating based on the actual offset position plus the write length, it uses a flawed amortized growth calculation that doesn't account for large offset gaps.

Root Cause

The root cause is an incorrect extent calculation formula in WriteBlob(). When determining how much to expand the blob's memory allocation, the original code calculated:

extent = blob_info->extent + blob_info->quantum + length

This formula fails when the current offset is significantly larger than the existing extent. The calculation should instead ensure the new extent accommodates the actual write position:

extent = offset + quantum + length

The vulnerable code path is triggered when processing image data that causes large seeks followed by writes, a pattern that can be controlled through malicious image file inputs.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. An attacker can exploit this vulnerability by:

1. Crafting a malicious image file that triggers large offset seeks during processing
2. Delivering the image to a target system that processes it through ImageMagick
3. The malicious file causes SeekBlob() to advance offset far beyond the current extent
4. Subsequent WriteBlob() calls write data beyond the allocated heap buffer
5. Controlled heap corruption enables arbitrary code execution

// Security patch in MagickCore/blob.c
// Source: https://github.com/ImageMagick/ImageMagick/commit/077a417a19a5ea8c85559b602754a5b928eef23e

   extent=(MagickSizeType) (blob_info->offset+(MagickOffsetType) length);
   if (extent >= blob_info->extent)
     {
-      extent=blob_info->extent+blob_info->quantum+length;
+      extent+=blob_info->quantum+length;
       blob_info->quantum<<=1;
       if (SetBlobExtent(image,extent) == MagickFalse)
         return(0);

The fix modifies the extent calculation to properly account for the current offset position by using the already-computed extent value (which includes offset + length) as the base for the expansion calculation.

Detection Methods for CVE-2025-57807

Indicators of Compromise

• Unexpected crashes or segmentation faults in ImageMagick processes during image processing
• Abnormal memory allocation patterns in convert, identify, or other ImageMagick utilities
• Presence of unusually structured image files with large internal offset values
• Core dumps indicating heap corruption in MagickCore/blob.c functions

Detection Strategies

• Monitor ImageMagick processes for abnormal memory access patterns using tools like Valgrind or AddressSanitizer
• Implement file integrity monitoring on ImageMagick binary files and libraries
• Deploy runtime application self-protection (RASP) to detect heap overflow attempts
• Use SentinelOne's behavioral AI to identify anomalous process behavior during image processing

Monitoring Recommendations

• Enable verbose logging for ImageMagick operations processing external or untrusted images
• Set up alerts for ImageMagick process crashes or unexpected terminations
• Monitor system logs for segmentation fault signals (SIGSEGV) from ImageMagick binaries
• Track memory allocation patterns for ImageMagick processes in production environments

How to Mitigate CVE-2025-57807

Immediate Actions Required

• Upgrade ImageMagick to version 14.8.2 or later immediately
• Audit systems for any ImageMagick installations using convert -version or package manager queries
• Restrict ImageMagick processing of untrusted images until patching is complete
• Implement input validation to filter potentially malicious image files before processing

Patch Information

ImageMagick has released version 14.8.2 which contains the fix for this vulnerability. The patch is available through the official ImageMagick GitHub commit. Additional details can be found in the GitHub Security Advisory GHSA-23hg-53q6-hqfg.

Debian users should refer to the Debian LTS Announcement for distribution-specific patching guidance.

Workarounds

• Implement strict ImageMagick policy restrictions to limit file format processing capabilities
• Use container isolation or sandboxing for ImageMagick processes handling untrusted content
• Deploy a web application firewall (WAF) with image validation rules for web-facing applications
• Consider using alternative image processing libraries for critical applications until patching

# Configuration example - Restrict ImageMagick processing via policy.xml
# Location: /etc/ImageMagick-7/policy.xml or similar

# Disable potentially dangerous coders
<policy domain="coder" rights="none" pattern="*" />
<policy domain="coder" rights="read|write" pattern="{PNG,JPEG,GIF,WEBP}" />

# Limit resource usage
<policy domain="resource" name="memory" value="256MiB"/>
<policy domain="resource" name="map" value="512MiB"/>
<policy domain="resource" name="width" value="16KP"/>
<policy domain="resource" name="height" value="16KP"/>
<policy domain="resource" name="area" value="128MP"/>