SurrealDB: Authenticated subscribers can read records hidden by SELECT permissions via LIVE subscriptions

A record user could read records the table's SELECT permission expression should have hidden, when that expression referenced $value, $before, $after, or $event. Binding a chosen value to that name before registering a LIVE SELECT caused notifications to evaluate the permission against the attacker's input instead of the real document.

Impact

A record user binds a value to $value, $before, $after, or $event (e.g. LET $value = [$auth.id]) and registers LIVE SELECT * FROM person. The captured value shadows the real document at notification time, so a SELECT permission like WHERE $auth.id.id() IN $value passes for every record on the table — the subscriber receives notifications for records they should not see.

Read-only impact, bounded to one table. Permission expressions that reference only field names, $auth, or $session are unaffected.

Patches

A patch has been introduced that re-orders the LIVE notification parameter binding so captured user variables are added first and the trusted document-context and session parameters are added last.

• Versions 3.1.0 and later are not affected by this issue.

Workarounds

Affected users who are unable to update should avoid table-PERMISSIONS and LIVE WHERE expressions that read user-named variables ($value, $before, $after, $event) without also gating on a system-derived field such as the record id.