CVE-2026-94094: OpenClaw Canvas Host Route server.ts createCanvasHostHandler denial of service
A flaw has been found in OpenClaw up to 2026.9.5. Affected is the function createCanvasHostHandler of the file extensions/canvas/src/host/server.ts of the component Canvas Host Route. Executing a manipulation can lead to denial of service. The attack can be launched remotely. The exploit has been published and may be used. Fix suggestion's "streaming/size-limit" was never shipped - latest 2026.9.5 still buffers the whole file via readFile() (src/canvas/serve.runtime.ts:17,114), unlike the sibling WS path which caps at 64KB. The vendor was contacted early about this disclosure.
Affected Software
Event History
Frequently Asked Questions
Which deployments are affected?
OpenClaw Canvas Host Route deployments running OpenClaw versions up to and including 2026.9.5 are affected. The available data does not identify a fixed release.
What access does an attacker need?
The issue can be exploited remotely and requires low privileges, as indicated by the PR:L vector. No user interaction is required.
Is the proposed size-limit mitigation present in the latest affected release?
No. The suggested streaming/size-limit change was not shipped; version 2026.9.5 still buffers the entire file through readFile(). The sibling WebSocket path has a 64 KB cap, but the affected route does not.