A `PERMISSIONS ... WHERE` clause is evaluated with permission enforcement disabled, so it can't recurse into its own checks. But the clause could also contain data-modifying statements, and these ran with enforcement still off — so evaluating a permission check could write to tables the caller cannot write. For example: ```surql DEFINE TABLE post PERMISSIONS FOR update WHERE (CREATE log SET at = time::now()) OR true; ``` Any user allowed to update a `post` now also creates a `log` record, even with no permission on `log`. The clause is evaluated once per matched record, so one statement can cause several writes. ### Impact Only databases with a `PERMISSIONS` clause that contains a write are affected; `FULL`, `NONE`, and read-only clauses are not. What an attacker **can** do: - With permission to perform the guarded operation (a low-privileged or record user is enough), write to tables in their own database that their permissions would otherwise forbid, by triggering an operation the clause guards. - Cause several writes from a single statement — the clause is evaluated once per matched record. - Trigger unintended events, cascades, or data corruption on those tables. What it **can't** do: - Escape the caller's own namespace and database — a permission clause cannot switch namespace or database. - Perform root- or namespace-level actions such as creating users; the caller's role still applies. - Read hidden data — this is an integrity issue, not disclosure. ### Patches Permission clauses must now be read-only: defining or importing one that contains a write is rejected, and any write attempted while a clause is evaluated is blocked at runtime, including writes reached through a called function. Read-only clauses are unaffected. - Versions 3.2.0 and later are not affected by this issue. ### Workarounds Users unable to patch should consider the following workarounds: - Review your `PERMISSIONS` clauses and remove any containing `CREATE`, `UPDATE`, `DELETE`, `RELATE`, `INSERT`, or `UPSERT`. - Limit who can define schema and vet imported data — such a clause must be defined before it can be triggered. ### Resources - [DEFINE TABLE … PERMISSIONS](https://surrealdb.com/docs/surrealql/statements/define/table) - [DEFINE FIELD](https://surrealdb.com/docs/surrealql/statements/define/field) - `fix(core): reject writes in PERMISSIONS clauses and block writes during permission evaluation` (included in SurrealDB 3.2.0) ### Acknowledgements Thank you to [sondt99](https://github.com/sondt99) for reporting this issue.