GHSA-c8vc-7pv3-g98p: Budibase: Email Change IDOR via POST /api/v2/email allows full Account Takeover (accountId not validated against session)

Summary POST /api/v2/email on the account portal (account.budibase.app) starts an email-change workflow using a client-supplied accountId that is not validated against the authenticated session. A logged-in attacker supplies a victim's accountId and an email address they control; the verification code is delivered to the attacker's address, and completing the workflow changes the victim's account email. The attacker then password-resets the victim's account through the controlled address and logs in — full account takeover with no victim interaction. Vulnerability Details The endpoint session-checks the currentEmail field (a mismatch returns 403), but it does not enforce body.accountId === session.accountId. The account-portal frontend only ever submits the logged-in user's own accountId, so in normal use the two always match — the server simply trusts the body value. An attacker who has a victim's accountId can point the workflow at the victim's account while passing their own currentEmail to clear the session check. This is more powerful than a direct password reset: PUT /api/v2/auth/password {email} already exists and is gated only on knowing the victim's email, but the reset link is sent to the address on the account — the victim's inbox, which the attacker does not control. This IDOR moves the victim's email to an attacker-controlled inbox first, so the attacker receives the reset link and sets a password they know. accountId obtainability. We checked every endpoint reachable from a non-admin free-tier account — GET /api/global/users (no UUID in any user record), GET /api/global/auditlogs/search (no accountId field), GET /api/global/users/invites (code + email + name only), GET /api/v2/tenant (one tenant-internal UUID, not a user accountId), the account-portal frontend (passes the session's own accountId only), and all unauthenticated endpoints — and the victim's accountId was not present in any of them. The attacker must obtain the UUID through some chann