CVE-2026-72856: Budibase before 3.40.0 Authentication Bypass via Tenant Owner Email
Budibase versions before 3.40.0 contain an authorization/authentication bypass in the PUT /api/global/users/tenant/owner (changeTenantOwnerEmail) endpoint. On self-hosted instances (SELFHOSTED or DISABLEACCOUNTPORTAL set), the cloudRestricted middleware is a no-op and the route is protected only by a general authentication check, so any authenticated user — including a lowest-privilege BASIC app user — can reassign the tenant account-holder (top-privilege admin) email to an attacker-controlled address. The attacker can then use the public password-reset flow to take over the admin account, leading to full administrative access.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Budibaseto a version that resolves this vulnerability.Fixed in 3.40.0 - Compensating control
On self-hosted instances, restrict access to the affected endpoint PUT /api/global/users/tenant/owner (changeTenantOwnerEmail) to trusted/administrative users only (e.g., via network controls or an application gateway/WAF rule), since cloudRestricted is a no-op when SELF_HOSTED or DISABLE_ACCOUNT_PORTAL is set and the route is otherwise protected only by a general authentication check.