CVE-2026-56377: ImageMagick Path Traversal Vulnerability

CVE-2026-56377 Overview

CVE-2026-56377 is a path traversal vulnerability [CWE-22] affecting ImageMagick versions prior to 7.1.2-24. The flaw stems from an incorrect policy check in the file path validation logic. Attackers with local access can bypass security policy restrictions and create or truncate files outside intended boundaries. Remote attackers can exploit sandboxed conversion services that expose ImageMagick to untrusted input. The vulnerability targets deployments that rely on ImageMagick's policy.xml restrictions to sandbox image conversion workflows. ImageMagick maintainers addressed the issue in the 7.1.2-24 release, published alongside a GitHub Security Advisory.

Critical Impact
Attackers can bypass ImageMagick path policies to write arbitrary files, potentially overwriting configuration files or planting content in web-accessible directories within sandboxed image conversion services.

Affected Products

ImageMagick versions prior to 7.1.2-24
Applications embedding ImageMagick for image conversion (web services, CMS platforms)
Sandboxed conversion services relying on policy.xml path restrictions

Discovery Timeline

2026-06-30 - CVE-2026-56377 published to NVD
2026-07-02 - Last updated in NVD database

Technical Details for CVE-2026-56377

Vulnerability Analysis

CVE-2026-56377 is a path traversal weakness classified under [CWE-22]. ImageMagick enforces access restrictions through its policy.xml configuration file, which administrators use to restrict coders, resources, and file system paths. The vulnerable code performs an incorrect check when validating output paths against these policy rules. As a result, files that should be disallowed by policy can still be created or truncated when the check misinterprets the target path.

The issue is particularly relevant for services that convert user-supplied images through ImageMagick binaries such as convert or magick. Operators typically deploy policy.xml as a hardening layer against previous ImageMagick vulnerabilities. This flaw undermines that hardening layer by allowing attackers to reach paths the policy was designed to block.

Root Cause

The root cause is an incorrect policy comparison in ImageMagick's path validation routine. The check does not correctly normalize or match the requested file path against the deny rules defined in policy.xml. Paths that should trigger a policy denial pass validation and reach the file write operation.

Attack Vector

Exploitation requires an attacker to supply a crafted output path to an ImageMagick operation, either directly through a local shell or indirectly through an application that forwards user input to ImageMagick. The attacker instructs ImageMagick to write output to a location prohibited by policy.xml. Because the policy check accepts the crafted path, ImageMagick creates or truncates the target file. Successful writes can corrupt configuration files, overwrite logs, or place attacker-controlled content in sensitive directories. For technical details, see the VulnCheck Advisory on ImageMagick and the GitHub Security Advisory.

Detection Methods for CVE-2026-56377

Indicators of Compromise

Unexpected file creation or truncation events originating from ImageMagick processes such as magick, convert, or mogrify.
Image conversion requests containing traversal sequences (../) or absolute paths targeting sensitive directories.
Modifications to configuration files or web-accessible directories with parent process identifiers tied to ImageMagick.

Detection Strategies

Audit application logs for image conversion requests where the output filename references paths outside the intended working directory.
Enable file integrity monitoring on directories referenced by ImageMagick policy.xml deny rules.
Correlate ImageMagick process execution with unexpected open() or creat() syscalls against protected paths.

Monitoring Recommendations

Log ImageMagick command invocations, including full arguments, from any wrapper service.
Monitor for policy.xml bypass patterns and alert on writes to system directories from image processing service accounts.
Track ImageMagick binary versions across the fleet and flag hosts running versions earlier than 7.1.2-24.

How to Mitigate CVE-2026-56377

Immediate Actions Required

Upgrade ImageMagick to version 7.1.2-24 or later on all systems and container images.
Inventory applications embedding ImageMagick libraries and rebuild them against the patched release.
Restrict operating system permissions for image conversion service accounts to the minimum required directories.

Patch Information

The ImageMagick project fixed CVE-2026-56377 in release 7.1.2-24. Release notes and remediation details are available in the GitHub Security Advisory GHSA-gm48-c7f2-v67p. Distribution maintainers have released updated packages through standard channels.

Workarounds

Run ImageMagick under a dedicated, unprivileged user with no write access to sensitive directories.
Execute ImageMagick inside a restrictive container or chroot environment that prevents writes outside a designated working directory.
Sanitize and canonicalize user-supplied output paths at the application layer before invoking ImageMagick.

bash

# Verify installed ImageMagick version and upgrade if needed
magick -version | head -n 1

# Debian/Ubuntu example
sudo apt-get update && sudo apt-get install --only-upgrade imagemagick

# Confirm the patched version is installed
magick -version | grep -E "7\.1\.2-2[4-9]|7\.1\.[3-9]"