CVE-2026-30931: ImageMagick Buffer Overflow Vulnerability

CVE-2026-30931 Overview

A heap-based buffer overflow vulnerability has been identified in ImageMagick, the widely-used open-source software for editing and manipulating digital images. This vulnerability exists in the UHDR encoder component and occurs due to improper truncation of a value, which can result in an out-of-bounds write condition. Successful exploitation could allow attackers to corrupt memory, potentially leading to denial of service or limited integrity impacts on systems processing malicious image files.

Critical Impact

Local attackers can exploit the heap-based buffer overflow in the UHDR encoder to cause denial of service through memory corruption, with potential for limited integrity compromise on vulnerable ImageMagick installations.

Affected Products

• ImageMagick versions prior to 7.1.2-16

Discovery Timeline

• 2026-03-10 - CVE-2026-30931 published to NVD
• 2026-03-11 - Last updated in NVD database

Technical Details for CVE-2026-30931

Vulnerability Analysis

This vulnerability is classified as CWE-122 (Heap-based Buffer Overflow), a memory corruption flaw that occurs when a program writes data beyond the allocated boundary of a heap buffer. In the context of ImageMagick's UHDR encoder, the vulnerability stems from improper handling of value truncation during the encoding process.

The UHDR (Ultra HDR) encoder processes image data and performs calculations that involve type conversions. When a value is truncated improperly—typically when a larger data type is converted to a smaller one without proper bounds checking—the resulting value can be significantly different from the original. This incorrect value is then used to determine write boundaries, allowing data to be written outside the intended heap buffer allocation.

The attack requires local access to the target system, as an attacker would need to provide a specially crafted image file to ImageMagick for processing. While no user interaction is required once the malicious file reaches the processing pipeline, the local attack vector limits the exposure compared to remotely exploitable vulnerabilities.

Root Cause

The root cause of this vulnerability lies in numeric truncation errors within the UHDR encoder's processing logic. When handling image encoding operations, the code performs arithmetic or type conversions that result in value truncation. This truncated value is subsequently used in memory allocation or boundary calculations, creating a mismatch between the expected buffer size and the actual data being written. The insufficient validation of truncated values before use in memory operations allows heap corruption to occur.

Attack Vector

The attack vector requires local access to the vulnerable system. An attacker would craft a malicious image file designed to trigger the truncation condition in the UHDR encoder. When ImageMagick processes this file—whether through direct command-line invocation, library API calls, or web application image processing pipelines—the heap-based buffer overflow is triggered.

The vulnerability mechanism can be described as follows: during UHDR encoding, a size or offset value undergoes truncation, resulting in an incorrect smaller value. When this value is used to control write operations, the encoder writes data past the allocated heap buffer boundary. This out-of-bounds write can corrupt adjacent heap metadata or application data, potentially causing denial of service through application crashes or memory corruption that affects application integrity.

For detailed technical analysis, refer to the GitHub Security Advisory.

Detection Methods for CVE-2026-30931

Indicators of Compromise

• Unexpected ImageMagick process crashes or segmentation faults during UHDR image encoding operations
• Abnormal memory consumption patterns in ImageMagick processes handling image conversions
• Application logs showing heap corruption or memory allocation failures during image processing
• Core dumps or crash reports referencing UHDR encoder functions

Detection Strategies

• Monitor ImageMagick process behavior for abnormal termination signals (SIGSEGV, SIGABRT) during image encoding operations
• Implement file integrity monitoring to detect potentially malicious image files targeting the UHDR encoder
• Deploy runtime application self-protection (RASP) solutions to detect heap overflow attempts
• Use memory sanitizers (AddressSanitizer, Valgrind) in development and testing environments to identify heap corruption

Monitoring Recommendations

• Configure centralized logging for ImageMagick operations and monitor for encoding failures
• Set up alerts for unusual patterns of ImageMagick crashes or restarts
• Monitor system resources (memory usage, CPU) for anomalies during image processing workloads
• Implement network monitoring to detect potentially malicious image file uploads in web applications using ImageMagick

How to Mitigate CVE-2026-30931

Immediate Actions Required

• Upgrade ImageMagick to version 7.1.2-16 or later immediately
• Audit systems to identify all ImageMagick installations across your environment
• Review and restrict file upload capabilities in web applications using ImageMagick for image processing
• Consider temporarily disabling UHDR encoding functionality if an immediate upgrade is not possible

Patch Information

This vulnerability is fixed in ImageMagick version 7.1.2-16. Organizations should upgrade to this version or later to remediate the heap-based buffer overflow in the UHDR encoder. The fix addresses the value truncation issue by implementing proper bounds checking before memory write operations.

Patch details and source code changes are available in the GitHub Security Advisory.

Workarounds

• Disable UHDR encoding capabilities through ImageMagick policy configuration if upgrading is not immediately feasible
• Implement strict input validation for image files before processing with ImageMagick
• Use sandboxing or containerization to isolate ImageMagick processes from critical system resources
• Configure ImageMagick resource limits to minimize the impact of potential memory corruption

# Configuration example - Disable UHDR encoding in policy.xml
# Location: /etc/ImageMagick-7/policy.xml or similar
# Add the following policy to restrict UHDR coder usage

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

# Verify ImageMagick version after upgrade
convert -version | grep Version