CVE-2026-56370: ImageMagick RCE Vulnerability

CVE-2026-56370 Overview

CVE-2026-56370 affects ImageMagick versions prior to 7.1.2-19. The vulnerability resides in the ConnectedComponentsImage() function, which mishandles connected-components artifacts containing invalid indices. Attackers supply malformed connected-components definitions through the command-line interface to trigger out-of-bounds memory access [CWE-125].

Successful exploitation causes access violations that result in denial of service. Memory corruption conditions may also enable code execution in specific configurations. The flaw requires local access and user interaction to exploit.

Critical Impact
Out-of-bounds read in ConnectedComponentsImage() allows local attackers to crash ImageMagick processes through crafted CLI arguments, with potential for code execution under certain conditions.

Affected Products

ImageMagick versions before 7.1.2-19
Applications and services that invoke ImageMagick CLI with untrusted artifact parameters
Linux and Unix distributions packaging vulnerable ImageMagick releases

Discovery Timeline

2026-06-24 - CVE-2026-56370 published to NVD
2026-06-25 - Last updated in NVD database

Technical Details for CVE-2026-56370

Vulnerability Analysis

The vulnerability resides in the ConnectedComponentsImage() function within ImageMagick. This function performs connected-components analysis on raster images, labeling regions of connected pixels for downstream processing. ImageMagick exposes tunable parameters for this analysis through artifacts set via the -define CLI flag.

When a user supplies a connected-components artifact, the function parses index values from the supplied string. The function does not validate that these indices fall within the bounds of the internal component array. An invalid index causes the routine to read memory outside the allocated buffer, producing an out-of-bounds access condition classified under [CWE-125].

The issue is local in nature because exploitation requires invoking the ImageMagick binary with attacker-controlled arguments. Workflows that pass untrusted user input directly into magick or convert command lines extend the attack surface considerably.

Root Cause

The root cause is missing bounds validation on indices parsed from the connected-components artifact. The function trusts the supplied index values and indexes into the components array without verifying that the values fall within 0..n-1 where n is the component count. Maintainers added bounds checks in version 7.1.2-19 to reject invalid indices before dereferencing.

Attack Vector

An attacker invokes ImageMagick with a malformed -define connected-components:... parameter on a target image. The parser accepts the malformed indices and the analysis function dereferences them, triggering the access violation. The vulnerability requires user interaction because a victim must execute the command or process the attacker-supplied image through a vulnerable workflow.

For technical details, see the GitHub Security Advisory and the VulnCheck Security Advisory.

Detection Methods for CVE-2026-56370

Indicators of Compromise

Unexpected segmentation faults or access violations in magick, convert, or identify processes
Core dumps generated by ImageMagick binaries during image conversion workloads
Process termination logs referencing ConnectedComponentsImage in stack traces

Detection Strategies

Inventory installed ImageMagick versions across endpoints and servers; flag any version earlier than 7.1.2-19
Inspect command-line telemetry for magick or convert invocations that pass -define connected-components: with externally sourced values
Review web application logs for image-processing endpoints that accept user-controlled processing parameters

Monitoring Recommendations

Enable process crash reporting for ImageMagick binaries and forward events to a centralized log platform
Monitor file processing services such as image upload pipelines for abnormal crash rates after deployment of patched binaries
Track invocation frequency of -define parameters by source process to identify automation that may pass untrusted input

How to Mitigate CVE-2026-56370

Immediate Actions Required

Upgrade ImageMagick to version 7.1.2-19 or later on all systems
Audit applications that wrap ImageMagick CLI tools and restrict user-controlled values passed to -define
Disable connected-components analysis in workflows that do not require it

Patch Information

The ImageMagick maintainers fixed CVE-2026-56370 in release 7.1.2-19 by adding bounds checks on indices parsed from the connected-components artifact. Refer to the GitHub Security Advisory GHSA-pmpg-6pww-fg6q for patch details. Linux distribution maintainers are publishing backported packages; apply distribution updates as they become available.

Workarounds

Sanitize or reject user-supplied values destined for ImageMagick -define parameters in upstream applications
Run ImageMagick under sandboxing or seccomp profiles to limit the blast radius of process crashes
Restrict the ImageMagick policy file (policy.xml) to disallow modules and resources not required by the workload

bash

# Verify installed ImageMagick version meets the patched release
magick -version | grep -i "Version: ImageMagick 7.1.2-19"

# Upgrade on Debian/Ubuntu once distribution packages are published
sudo apt update && sudo apt install --only-upgrade imagemagick

# Upgrade on RHEL/Fedora
sudo dnf upgrade ImageMagick