CVE-2026-25971: ImageMagick Buffer Overflow Vulnerability

CVE-2026-25971 Overview

A stack overflow vulnerability has been identified in ImageMagick, the widely-used open-source software for editing and manipulating digital images. The flaw exists in how Magick processes MSL (Magick Scripting Language) files, where the application fails to check for circular references between two MSLs. This oversight can lead to infinite recursion, ultimately causing a stack overflow condition.

Critical Impact

Attackers can exploit this vulnerability remotely without authentication to potentially crash the application or execute arbitrary code by crafting malicious MSL files with circular references.

Affected Products

• ImageMagick versions prior to 7.1.2-15
• ImageMagick versions prior to 6.9.13-40
• Applications and services utilizing vulnerable ImageMagick libraries for image processing

Discovery Timeline

• 2026-02-24 - CVE-2026-25971 published to NVD
• 2026-02-25 - Last updated in NVD database

Technical Details for CVE-2026-25971

Vulnerability Analysis

This vulnerability (CWE-674: Uncontrolled Recursion, CWE-787: Out-of-bounds Write) stems from improper handling of MSL file references in ImageMagick. When processing MSL scripts, the application does not validate whether circular dependencies exist between MSL files. An attacker can craft two or more MSL files that reference each other, causing the parser to enter an infinite recursive loop.

As the recursion continues unchecked, each function call consumes stack memory until the stack is exhausted, resulting in a stack overflow. This can lead to application crashes (denial of service) or, in certain conditions, could potentially be leveraged for arbitrary code execution if an attacker can control memory layout.

Root Cause

The root cause lies in the MSL parsing logic within ImageMagick, which lacks validation for circular references between MSL files. When an MSL file includes or references another MSL file, and that file references back to the original (either directly or through a chain), the parser follows these references indefinitely. The absence of a reference tracking mechanism or recursion depth limit allows this uncontrolled recursion to occur.

Attack Vector

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

1. Crafting malicious MSL files containing circular references
2. Uploading or submitting these files to any application or service that processes images using vulnerable ImageMagick versions
3. The malicious files trigger the recursive parsing behavior, causing stack exhaustion

This is particularly dangerous for web applications, content management systems, and image processing services that automatically process user-uploaded images with ImageMagick.

The vulnerability can be triggered through any interface that accepts and processes MSL files, including command-line tools like convert or magick, as well as library API calls. For technical details on the vulnerability mechanism, see the GitHub Security Advisory.

Detection Methods for CVE-2026-25971

Indicators of Compromise

• Unexpected application crashes in ImageMagick processes with stack overflow error messages
• Abnormally high memory consumption in image processing services
• Core dumps or crash logs indicating recursive function calls in MSL parsing routines
• Unusual MSL file uploads or processing requests from external sources

Detection Strategies

• Monitor for stack overflow exceptions in applications using ImageMagick libraries
• Implement file type validation to detect and flag MSL files before processing
• Deploy application-level logging to track ImageMagick processing operations and identify recursive patterns
• Use runtime application security monitoring to detect anomalous recursion behavior

Monitoring Recommendations

• Configure crash reporting systems to alert on ImageMagick process terminations
• Implement resource usage monitoring for memory and CPU consumption spikes during image processing
• Enable verbose logging in ImageMagick to capture processing errors and warnings
• Monitor upload endpoints for suspicious file patterns or repeated upload attempts

How to Mitigate CVE-2026-25971

Immediate Actions Required

• Upgrade ImageMagick to version 7.1.2-15 or later (for 7.x branch)
• Upgrade ImageMagick to version 6.9.13-40 or later (for 6.x branch)
• Audit systems to identify all ImageMagick installations and dependent applications
• Implement input validation to restrict or sanitize MSL file processing

Patch Information

ImageMagick has released patched versions that address this vulnerability by implementing proper circular reference detection in MSL parsing. The fix is available in versions 7.1.2-15 and 6.9.13-40. Organizations should update to these versions or later as soon as possible.

For more information, refer to the GitHub Security Advisory.

Workarounds

• Disable MSL processing entirely if not required by configuring ImageMagick's policy.xml file
• Implement strict file type validation to reject MSL files at the application layer
• Use containerization or sandboxing to isolate ImageMagick processes and limit the impact of potential crashes
• Configure resource limits (ulimit) to cap stack size and prevent unbounded growth

# Configuration example - Disable MSL in ImageMagick policy.xml
# Add this to /etc/ImageMagick-7/policy.xml or equivalent
<policy domain="coder" rights="none" pattern="MSL" />