GHSA-gp79-m99v-gjmh: OpenClaw: Mattermost handlers could fall open when channel type was missing

Mattermost handlers could fall open when channel type was missing. In affected versions, a Mattermost event missing channel type metadata could continue without applying the intended DM policy decision.

This advisory is scoped to the named feature and configuration. It does not change OpenClaw’s trusted-operator model: authenticated Gateway operators, installed plugins, and intentional local execution surfaces remain trusted unless a separate policy, approval, allowlist, sandbox, or auth boundary is crossed.