CVE-2026-25983: ImageMagick Use-After-Free Vulnerability

CVE-2026-25983 Overview

A critical use-after-free vulnerability has been identified in ImageMagick, the widely-used open-source software for editing and manipulating digital images. This vulnerability exists in how ImageMagick processes crafted MSL (Magick Scripting Language) scripts. When a specially crafted MSL script is processed, the operation element handler replaces and frees an image object while the parser continues reading from it, resulting in a heap-use-after-free condition in the ReadBlobString function during further parsing.

Critical Impact

This use-after-free vulnerability could allow remote attackers to execute arbitrary code, cause denial of service, or potentially gain unauthorized access to sensitive information by exploiting memory corruption through malicious MSL script files.

Affected Products

• ImageMagick versions prior to 7.1.2-15
• ImageMagick versions prior to 6.9.13-40
• Any application or service that processes untrusted image files using vulnerable ImageMagick versions

Discovery Timeline

• 2026-02-24 - CVE-2026-25983 published to NVD
• 2026-02-25 - Last updated in NVD database

Technical Details for CVE-2026-25983

Vulnerability Analysis

This vulnerability is classified as CWE-416 (Use After Free), a critical memory corruption vulnerability type. The flaw resides in ImageMagick's MSL script processing functionality, specifically in how the parser handles image operations. The vulnerability occurs when a maliciously crafted MSL script triggers an operation element handler that replaces and frees the current image object. However, the parser continues to read from this freed memory location during subsequent parsing operations, specifically within the ReadBlobString function.

Use-after-free vulnerabilities are particularly dangerous because they can lead to various exploitation outcomes depending on how the freed memory is reallocated and what data is placed in that memory region. An attacker could potentially achieve arbitrary code execution by carefully controlling the memory state after the free operation.

Root Cause

The root cause lies in the MSL parser's failure to properly synchronize the image object lifecycle with the parsing state. When the operation element handler processes certain operations, it replaces and deallocates the current image structure. The parser, however, maintains a stale reference to this freed memory and continues to invoke ReadBlobString using the invalid image blob pointer. This disconnect between object management and parser state creates the exploitable condition.

Attack Vector

The attack vector for this vulnerability is network-based. An attacker can exploit this vulnerability by:

1. Crafting a malicious MSL script file designed to trigger the use-after-free condition
2. Delivering the malicious file to a target system through various means such as web uploads, email attachments, or other file sharing mechanisms
3. When the vulnerable ImageMagick installation processes the malicious MSL script, the use-after-free condition is triggered
4. Depending on memory layout and attacker skill, this could lead to code execution, information disclosure, or application crash

Since no user interaction is required beyond the application processing the malicious file, and no privileges are needed, this vulnerability presents a significant risk to systems that process untrusted image files with ImageMagick.

Detection Methods for CVE-2026-25983

Indicators of Compromise

• Unexpected crashes or segmentation faults in ImageMagick processes when handling MSL files
• Memory corruption errors or heap corruption detected in application logs
• Unusual MSL script files with complex nested operation elements in upload directories
• Process anomalies in convert, identify, mogrify, or other ImageMagick utilities

Detection Strategies

• Monitor ImageMagick process execution for abnormal termination signals (SIGSEGV, SIGABRT)
• Implement file type validation to detect MSL scripts being submitted through unexpected channels
• Deploy memory safety tools in development and staging environments to detect heap-use-after-free conditions
• Use application-level monitoring to track ImageMagick invocations with MSL file inputs

Monitoring Recommendations

• Enable detailed logging for all ImageMagick operations, particularly those involving MSL script processing
• Configure crash dump collection for ImageMagick processes to aid in incident investigation
• Implement rate limiting and anomaly detection for image processing operations
• Monitor for unusual patterns of MSL file submissions or processing requests

How to Mitigate CVE-2026-25983

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
• Review and audit all systems where ImageMagick processes untrusted input files
• Consider temporarily disabling MSL script processing if not required for business operations

Patch Information

ImageMagick has released patches addressing this vulnerability in versions 7.1.2-15 and 6.9.13-40. The patches resolve the synchronization issue between the operation element handler and the parser, ensuring that freed image objects are no longer accessed during parsing. For detailed patch information and technical analysis, refer to the GitHub Security Advisory.

Organizations should prioritize patching systems that process untrusted image files, particularly web servers, image processing services, and content management systems.

Workarounds

• Disable MSL coders by configuring ImageMagick's policy.xml to restrict MSL file processing
• Implement strict input validation to reject MSL script files from untrusted sources
• Use containerization or sandboxing to isolate ImageMagick processes and limit potential impact
• Apply principle of least privilege to ImageMagick processes to minimize exploitation consequences

# Configuration example - Disable MSL processing in policy.xml
# Add the following to /etc/ImageMagick-7/policy.xml or equivalent
# within the <policymap> section:

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