CVE-2026-33905

What it actually does

CVE-2026-33905 is an out-of-bounds read in ImageMagick's `-sample` image operation when a crafted `sample:offset` define is supplied. A local user, or a remote attacker who can cause an application to process attacker-controlled images or ImageMagick command options, can trigger invalid memory reads during image sampling. The primary technical consequence is process instability or crash, resulting in denial of service for the ImageMagick process or the calling application. The published CVSS vector indicates user interaction is required, privileges are not required, and the expected impact is availability rather than confidentiality or integrity compromise.

Why it matters to the business

Systems and applications that use ImageMagick to process uploaded, emailed, or otherwise untrusted images may be vulnerable to crashes or service disruption. The most likely operational impact is failed image processing, broken media workflows, queue backlogs, degraded web application functionality, or denial of service in services that automatically invoke ImageMagick. The vulnerability is not listed in CISA KEV, has low EPSS, no known exploit maturity, and no ransomware association, so broad active exploitation is not currently indicated; however, ImageMagick is widely embedded in application stacks, making exposure easy to overlook.

How an attack unfolds

An attacker prepares an image-processing request or workflow that invokes ImageMagick with the `-sample` operation and a specially chosen `sample:offset` define. When a vulnerable ImageMagick version below 6.9.13-44 or 7.1.2-19 processes the input, the sampling code uses the crafted offset in a way that reads outside the intended memory bounds. In typical real-world scenarios, exploitation would occur through a web application, API, batch processor, CI job, document conversion pipeline, or media service that accepts untrusted files or parameters and passes them to ImageMagick. Successful exploitation is expected to crash or destabilize the ImageMagick process or its parent service, causing denial of service rather than data theft or code execution based on currently available information.

How to fix it

Upgrade ImageMagick to a fixed release: version 6.9.13-44 or later for the 6.x branch, or version 7.1.2-19 or later for the 7.x branch. If ImageMagick is installed through an operating system package manager, apply the vendor-provided security update even if the displayed upstream version appears older, because distributions may backport fixes. Rebuild or redeploy containers, serverless images, CI runners, desktop packages, and application bundles that include ImageMagick libraries or command-line tools. Where immediate upgrade is not possible, restrict ImageMagick processing to trusted inputs, block user control of ImageMagick defines and command-line options, disable or tightly wrap use of `-sample` where feasible, enforce resource limits and worker isolation, and run ImageMagick under least-privilege sandboxing such as containers, seccomp/AppArmor/SELinux profiles, or dedicated non-privileged service accounts.

How to confirm the fix worked

Confirm that all reachable ImageMagick installations report a fixed version by running `magick -version`, `convert -version`, or package-manager inventory checks and verifying versions are 6.9.13-44/7.1.2-19 or later, or contain the applicable vendor backport. Validate container images and application bundles, not only base hosts, because ImageMagick is often embedded in runtime images. Review application code and job definitions for invocations of `-sample` and `-define sample:offset=...`, especially where options can be influenced by users. After patching, rerun representative image-processing workflows and negative tests using malformed or boundary-case sampling offsets to confirm the process no longer crashes. Confirm that resource limits, sandboxing, and input validation remain in place for services that process untrusted media.

Typical attack path

1. Identify an application or service that uses ImageMagick for image conversion, resizing, thumbnailing, or media preprocessing.
2. Determine whether user-controlled files or image-processing parameters can reach ImageMagick.
3. Submit a crafted image-processing request that causes ImageMagick to invoke `-sample` with a malicious `sample:offset` define.
4. Trigger the vulnerable out-of-bounds read during the sampling operation.
5. Cause the ImageMagick process, worker, or dependent application component to crash or fail processing jobs.
6. Repeat requests to create sustained denial of service, queue exhaustion, or operational disruption.

How to detect it

To assess possible prior exploitation, review logs from applications and services that invoke ImageMagick, including web upload handlers, API gateways, media-processing workers, batch queues, CI jobs, mail/document conversion systems, and container logs. Look for requests, job payloads, command lines, or error messages containing `sample:offset`, especially in combination with `-sample`, `magick`, `convert`, or `mogrify`. Correlate these events with crashes, segmentation faults, abnormal worker exits, restart loops, failed image-processing jobs, queue spikes, HTTP 5xx responses, or service health-check failures. On Linux, examine syslog, journald, kernel logs, container runtime logs, supervisor logs, coredump records, and application exception traces for ImageMagick crashes around the same timestamps. If core dumps are available, confirm whether the crashing process was ImageMagick or an application linked to ImageMagick libraries and whether the crash occurred during sampling logic. No public threat actors, KEV exploitation, or ransomware campaigns are currently associated with this issue, so detection should focus on suspicious crafted use of the vulnerable option and denial-of-service symptoms rather than known attacker infrastructure.

• sample:offset
• -define sample:offset
• -sample
• magick -define sample:offset
• convert -define sample:offset
• mogrify -define sample:offset
• Segmentation fault
• core dumped
• AddressSanitizer: heap-buffer-overflow
• AddressSanitizer: global-buffer-overflow
• AddressSanitizer: stack-buffer-overflow
• out of bounds read
• out-of-bounds read
• MagickCore
• ImageMagick

What your security team should do

• Inventory ImageMagick across servers, containers, developer workstations, CI/CD runners, and application dependencies using package inventory, SBOMs, and runtime discovery.
• Prioritize patching internet-facing or multi-tenant services that process untrusted images, uploads, email attachments, documents, or media conversion jobs.
• Upgrade to ImageMagick 6.9.13-44 or 7.1.2-19 or later, or apply the relevant operating-system vendor security update with a backported fix.
• Search application code, job templates, shell wrappers, and logs for `sample:offset` and user-controllable ImageMagick command construction.
• Ensure user input cannot directly control ImageMagick command-line options, defines, coders, delegates, or policy settings.
• Run ImageMagick workloads in isolated, least-privilege workers with CPU, memory, file-size, and execution-time limits to reduce denial-of-service impact.
• Monitor for repeated ImageMagick crashes, worker restarts, abnormal media-processing failures, and requests containing `sample:offset`.
• Because EPSS is low and there is no KEV listing or known exploit maturity, handle this as normal-priority patching unless the organization exposes ImageMagick processing to untrusted users, in which case treat it as higher priority.