CVE-2026-62363 Overview
CVE-2026-62363 is a heap buffer over-write vulnerability in ImageMagick, the open-source image editing and manipulation library. The flaw exists in the fx operation, which processes mathematical expressions applied to image data. Attackers can trigger the overflow by passing a crafted argument to the fx operation. The issue affects all ImageMagick versions prior to 7.1.2-27 and is classified under CWE-787 (Out-of-bounds Write). The maintainers resolved the issue in version 7.1.2-27.
Critical Impact
Local attackers with low privileges can trigger a heap buffer over-write in the ImageMagick fx operation, leading to process crashes and potential denial of service in applications processing untrusted image workloads.
Affected Products
- ImageMagick versions prior to 7.1.2-27
- Applications and services embedding vulnerable ImageMagick libraries
- Image processing pipelines that expose the fx operator to untrusted input
Discovery Timeline
- 2026-07-30 - CVE-2026-62363 published to NVD
- 2026-07-30 - Last updated in NVD database
Technical Details for CVE-2026-62363
Vulnerability Analysis
The vulnerability resides in ImageMagick's fx operation, an expression evaluator that lets users apply mathematical formulas to pixel data. When the operator receives a specially crafted argument, memory is written past the end of an allocated heap buffer. The out-of-bounds write [CWE-787] can corrupt adjacent heap metadata or object state.
Exploitation requires local access and user interaction, and the immediate impact is on availability. Confidentiality and integrity are not directly affected according to the published metrics. Applications that surface ImageMagick's fx operator to less-trusted users, such as web upload processors, scripting frontends, and automated conversion pipelines, are the most exposed.
See the GitHub Security Advisory for the maintainer's technical description.
Root Cause
The root cause is missing bounds enforcement inside the fx expression evaluator. When parsing or evaluating a crafted argument, the code writes beyond the allocated heap region. This class of defect commonly stems from incorrect size calculations, off-by-one indexing, or failure to validate expression complexity before allocating working buffers.
Attack Vector
An attacker supplies a crafted fx argument, either directly through the magick/convert command-line utilities or indirectly through an application that forwards user-controlled parameters to ImageMagick. Successful triggering corrupts heap memory in the ImageMagick process. The attack requires local privileges and user interaction, limiting remote exploitability but leaving multi-tenant hosts and automated pipelines exposed.
No public exploit code or proof-of-concept has been referenced in the advisory. Refer to the ImageMagick advisory for details on the affected code paths.
Detection Methods for CVE-2026-62363
Indicators of Compromise
- Repeated crashes or SIGABRT/SIGSEGV terminations of magick, convert, or embedded ImageMagick worker processes
- Heap corruption messages from glibc such as malloc(): corrupted top size in application or system logs
- Unusual fx operator invocations with long or deeply nested expressions in job queues or command histories
Detection Strategies
- Inventory installed ImageMagick versions across servers, containers, and developer workstations and flag any release earlier than 7.1.2-27
- Enable core dump collection for image-processing services and inspect crashes for fx-related call stacks
- Instrument image workflows with AddressSanitizer or Valgrind in staging environments to surface heap over-writes
Monitoring Recommendations
- Alert on ImageMagick processes exiting abnormally, particularly under user-supplied argument workloads
- Log every fx argument passed to ImageMagick when invoked from web or API tiers, and cap argument length
- Track version drift in container images and package inventories to detect regressions after patching
How to Mitigate CVE-2026-62363
Immediate Actions Required
- Upgrade ImageMagick to version 7.1.2-27 or later on all systems
- Rebuild and redeploy container images that bundle ImageMagick, then restart dependent services
- Restrict use of the fx operator to trusted inputs until patching is complete
Patch Information
The issue is fixed in ImageMagick 7.1.2-27. Package maintainers for major Linux distributions typically backport ImageMagick fixes; consult your distribution's security tracker and apply vendor updates as they become available. Reference: GitHub Security Advisory GHSA-422r-8c97-xcg4.
Workarounds
- Disable or block the fx coder in ImageMagick's policy.xml if immediate patching is not possible
- Sanitize and length-limit any user-supplied strings before passing them to ImageMagick command-line utilities
- Run ImageMagick under a low-privileged, sandboxed service account with resource limits to contain crashes
# Configuration example: disable the fx coder via ImageMagick policy.xml
# Edit /etc/ImageMagick-7/policy.xml and add within <policymap>:
<policy domain="coder" rights="none" pattern="FX" />
# Verify ImageMagick version after upgrading
magick -version | head -n 1
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
