GHSA-pvcr-8mvp-w8qr

### Summary The Budibase AI chat-link handoff flow (`GET/POST /api/chat-links/:instance/:token/handoff`) binds an **external chat identity** (Slack/Discord/MS Teams/Telegram) to a **Budibase user account**. The confirmation endpoint is on a **public route** (no CSRF middleware, no auth-group gate) and the only credential it checks is a `confirmationToken` that is **already rendered in plaintext into the HTML confirmation page** the victim views. There is no binding between the confirmation token and the requester's Budibase session at preparation time, and no CSRF token on the POST. Consequently, an attacker who creates a chat-link session for **their own** external chat identity (or any identity they can mint in their chat platform) can induce a victim Budibase user (same tenant) to submit the confirmation POST -> for example by sending them a link that auto-submits, or by XSS/CSRF on a co-tenanted page -> and the victim's `globalUserId` becomes bound to the attacker's external identity. The attacker then sends messages to the AI agent from their chat platform and is **acting as the victim user** inside Budibase automations/agent operations, inheriting the victim's permissions on agent operations, knowledge sources, and any downstream automation steps keyed off the linked identity. --- ### Affected | Component | Path | Lines | |---|---|---| | Public handoff routes (no auth-group middleware) | `packages/server/src/api/routes/chat.ts` | `23` (`GET /api/chat-links/:instance/:token/handoff`), `27` (`POST .../handoff`) | | Confirmation controller | `packages/server/src/api/controllers/ai/chatIdentityLinks.ts` | `124-177` (`confirmChatLinkSession`); the binding at `153-173` | | Confirmation token rendered into HTML | `packages/server/src/api/controllers/ai/chatIdentityLinks.ts` | `40-60` (`renderLinkConfirmationPage`); the hidden input at `55` | | Session creation (attacker side) | `packages/server/src/sdk/workspace/ai/chatIdentityLinks.ts` | `138-171` (`createChatI