CVE-2026-56363: ImageMagick Division by Zero Denial of Service

Technical summary

CVE-2026-56363 is a division-by-zero flaw stemming from insufficient validation of binomial kernel parameters in ImageMagick's kernel processing logic. The vulnerability chains an integer overflow (CWE-190) with an unchecked division operation. When a user or automated process supplies a crafted image or kernel specification with an excessively large binomial coefficient value, the integer overflow silently wraps to a small or zero value, which is then used as a divisor in a subsequent calculation. The resulting arithmetic fault causes the ImageMagick process to terminate abnormally. Attack surface is limited to local access scenarios where an attacker can influence kernel input—typically through malformed image files or direct API calls.

Business impact

The primary business impact is application availability. Any service or workflow that depends on ImageMagick for image processing—such as web-based image upload/resizing platforms, batch image conversion pipelines, or automated thumbnail generation—could experience sudden crashes when processing a malicious image. Because the CVSS score is low (3.3) and the attack vector is local with user interaction required, the risk is constrained to environments where untrusted image input is processed. Organizations running ImageMagick in isolated batch processing environments face lower risk than those exposing ImageMagick directly to user uploads without isolation.

Affected systems

ImageMagick versions before 7.1.2-22 are affected. This includes stable releases, older long-term support versions, and any derivative or embedded usage of the affected codebase. Verify your installed version against vendor advisories to confirm applicability. Third-party tools, web applications, and services that bundle ImageMagick as a dependency should be assessed; many may not update immediately once a patched ImageMagick version is released.

Exploitability

Exploitability is low in practical terms. The attack requires local access (AV:L), no special privileges (PR:N), but does require user interaction (UI:R)—meaning an attacker must induce a user to open or process a malicious image file. There is no known public exploit code listed in the KEV catalog. The vulnerability is not currently tracked as an active exploitation threat. However, once details are widely disclosed, attackers may craft proof-of-concept code to test ImageMagick deployments in batch environments or content delivery workflows.

Remediation

Upgrade ImageMagick to version 7.1.2-22 or later. The fix addresses the integer overflow validation and prevents the division by zero. Apply patches as soon as feasible, prioritizing systems that process untrusted image input. For organizations unable to patch immediately, restrict local access to ImageMagick processes, implement input validation to reject suspicious kernel parameters, and deploy ImageMagick in sandboxed or containerized environments to limit crash scope.

Patch guidance

Consult the official ImageMagick project release notes and security advisories for exact patch versions available for your distribution and platform. The fix is expected to be incorporated in ImageMagick 7.1.2-22 and later releases. If using ImageMagick through a Linux distribution package manager, check for available security updates; some distributions may backport the fix to older release series. For embedded or custom builds, obtain the upstream patch or rebuild against patched source code.

Detection guidance

Monitor ImageMagick process crashes or abnormal exits, particularly in log aggregation systems if your application logs ImageMagick errors. Look for application-level errors related to 'division by zero' or sudden termination of image processing jobs. Network-based detection is limited since the attack is local; however, file integrity monitoring or sandboxed execution environments may flag crafted image files if they exhibit unusual kernel specifications. Organizations may also implement input validation layers that reject suspiciously large kernel parameters before they reach ImageMagick.

Why prioritize this

This vulnerability warrants medium-to-low priority for most organizations due to its low CVSS score, local attack vector requirement, and need for user interaction. Prioritize patching if your organization: (1) processes untrusted image uploads from users, (2) runs automated batch image processing on externally sourced content, or (3) integrates ImageMagick into customer-facing services. Organizations that use ImageMagick only for internal, trusted image processing can defer patching slightly but should not ignore it indefinitely. The lack of KEV listing and active exploitation reports suggests this is a measured, not emergency, remediation scenario.

Risk score, explained

The CVSS 3.1 score of 3.3 (LOW) reflects the confluence of local attack vector (AV:L), low attack complexity (AC:L), no privileges required (PR:N), user interaction required (UI:R), and impact limited to availability (A:L). The scoring correctly captures that this is primarily a local denial-of-service with limited blast radius. The score does not account for business context—organizations heavily dependent on ImageMagick availability may perceive higher risk—but from a pure vulnerability perspective, the technical metrics justify a low rating.

Frequently asked questions