CVE-2026-56376: ImageMagick Use-After-Free Vulnerability

CVE-2026-56376 Overview

CVE-2026-56376 is a heap use-after-free vulnerability [CWE-416] in ImageMagick versions before 7.1.2-15 and 6.9.13-40. The flaw resides in the meta coder component. When memory allocation fails during image processing, ImageMagick writes a single byte to a stale pointer. Remote attackers can trigger this condition by submitting specially crafted image files to applications that use ImageMagick for image conversion or processing. Successful exploitation leads to a denial of service condition in the affected process.

Critical Impact
Remote attackers can crash ImageMagick processes by supplying crafted image files, disrupting any service that processes untrusted images through the library.

Affected Products

ImageMagick versions prior to 7.1.2-15
ImageMagick 6.x versions prior to 6.9.13-40
Applications and services that embed or invoke vulnerable ImageMagick builds for image processing

Discovery Timeline

2026-06-23 - CVE-2026-56376 published to NVD
2026-06-24 - Last updated in NVD database

Technical Details for CVE-2026-56376

Vulnerability Analysis

The vulnerability exists in the meta coder of ImageMagick, the module responsible for handling image metadata streams. When ImageMagick attempts to allocate memory during meta coder operations and the allocation fails, the error handling path does not correctly invalidate or guard a heap pointer. The code subsequently writes a single byte through this stale pointer, producing a use-after-free condition. While the write is limited in size, dereferencing freed memory corrupts heap state and reliably crashes the process. The Exploit Prediction Scoring System (EPSS) currently rates active exploitation likelihood as low, and no public proof-of-concept or exploit code has been observed.

Root Cause

The root cause is improper handling of an allocation failure in the meta coder. The code path that handles the failed allocation continues to use a pointer referencing already-freed or stale heap memory. A single-byte write through that pointer produces the use-after-free behavior tracked under [CWE-416]. The defect requires the attacker to influence allocator state so that the failure path is reached, which contributes to the high attack complexity rating.

Attack Vector

The vulnerability is reachable over the network whenever an application processes attacker-controlled image input with a vulnerable ImageMagick build. Common exposure points include web upload endpoints, document conversion pipelines, thumbnail generators, and content management systems that invoke convert, magick, or the MagickWand and MagickCore APIs. The attacker submits a crafted image file engineered to drive the meta coder into the failed-allocation path, triggering the stale-pointer write and crashing the worker process.

No verified public exploit code is available. Refer to the GitHub Security Advisory and the Vulncheck Advisory: ImageMagick Heap Use After Free for additional technical detail.

Detection Methods for CVE-2026-56376

Indicators of Compromise

Repeated crashes or SIGSEGV terminations of ImageMagick worker processes (magick, convert, identify) coincident with image upload activity
Core dumps showing faults inside meta coder routines or heap manipulation functions
Sustained inbound submissions of unusual or malformed image files targeting upload or conversion endpoints

Detection Strategies

Inventory hosts and containers running ImageMagick and compare installed versions against 7.1.2-15 and 6.9.13-40 to identify exposed assets
Monitor application logs and process supervisors for abnormal termination of image processing workers
Inspect web access logs for high-volume or anomalous image uploads followed by HTTP 5xx errors from conversion endpoints

Monitoring Recommendations

Aggregate ImageMagick process telemetry, crash signals, and upload endpoint logs in a centralized analytics platform for correlation
Alert on repeated worker crashes from the same source IP or session within a short time window
Track the rate of failed image conversions per upload endpoint and trigger investigation on sudden spikes

How to Mitigate CVE-2026-56376

Immediate Actions Required

Upgrade ImageMagick to version 7.1.2-15 or later, or to 6.9.13-40 or later on the 6.x branch
Apply distribution-provided security updates for any package that bundles ImageMagick
Audit applications that process user-supplied images and restart services after patching to clear vulnerable processes from memory

Patch Information

Fixed versions are ImageMagick 7.1.2-15 and 6.9.13-40. Patch and advisory details are published in the GitHub Security Advisory GHSA-2gq3-ww97-wfjm. Operators using vendor packages should track downstream backports from their Linux distribution security teams.

Workarounds

Restrict accepted image formats and reject unnecessary or rarely used coders at the application layer
Disable the meta coder and other unused coders in policy.xml to reduce attack surface until patches are applied
Run ImageMagick in a sandboxed or resource-limited worker with automatic restart so a single crash does not degrade service availability

bash

# Example ImageMagick policy.xml restriction to disable the meta coder
# Place inside the <policymap> element of /etc/ImageMagick-7/policy.xml
<policy domain="coder" rights="none" pattern="META" />
<policy domain="coder" rights="none" pattern="EPHEMERAL" />
<policy domain="resource" name="memory" value="256MiB" />
<policy domain="resource" name="disk" value="1GiB" />