OpenClaw: Webchat audio embedding could read local files without local-root containment

Summary

## Impact OpenClaw deployments before `2026.4.15` could embed host-local audio files into webchat responses without applying the local media root containment check used by other media-serving paths. If an attacker could influence an agent or tool-produced `ReplyPayload.mediaUrl`, the webchat audio embedding helper could resolve an absolute local path or `file:` URL, read an audio-like file under the size cap, and base64-encode it into the webchat media response. This crossed the model/tool-output boundary into a host file read. Prompt injection or malicious tool output is a delivery mechanism; the security boundary failure is the missing local-root containment check. The impact is narrow: the file had to be readable by the gateway process, have an audio-like extension, and fit within the webchat audio size cap. The issue exposed contents into the webchat assistant/media transcript path; it was not a general remote filesystem API. ## Affected Packages / Versions - Package: `openclaw` on npm - Affected versions: `<= 2026.4.14` - Patched version: `2026.4.15` The latest public release, `2026.4.21`, also contains the fix. ## Patches The public fix threads the applicable local media roots into the webchat audio embedding path and calls `assertLocalMediaAllowed` before local audio content is read. Current `main` also includes an additional `trustedLocalMedia` gate so untrusted model/tool payloads cannot opt into local audio embedding. Fix commit: - `6e58f1f9f54bca1fea1268ec0ee4c01a2af03dde` ## Workarounds Upgrade to `[email protected]` or later. The latest public release, `2026.4.21`, is fixed. Before upgrading, avoid exposing webchat sessions to untrusted prompt/tool content that can influence reply media URLs. ## Credits OpenClaw thanks @zsxsoft for reporting.