EEF-CVE-2026-86338

Ash field policies do not filter-nil forbidden calculations and aggregates, enabling an information-disclosure oracle

## Summary Ash `field_policies` are documented to protect against filter-based information disclosure: when a field the actor may not see is referenced in a filter, it is replaced with an expression that evaluates to `nil`, so a filter cannot be used as a yes/no oracle to read a value the actor cannot see. This nilling was applied to attributes but not to calculations or aggregates. A user-supplied filter reference to a calculation or aggregate carries an `Ash.Query.Calculation` / `Ash.Query.Aggregate` struct, which the authorizer's reference replacement did not match (it only matched the `Ash.Resource.*` structs), so the filter ran against the real value. As a result, an actor whose field policies forbid a calculation or aggregate can still filter by it (for example `filter(secret_calc == "x")` or `filter(comment_count == n)`) and learn the value from whether rows match — an oracle that recovers field-policy-protected values one probe at a time. Filtering is commonly exposed to lower-privileged actors (for example via AshGraphql or AshJsonApi filter arguments), which is exactly the surface field policies are meant to protect. The fix routes filter references to calculations and aggregates through the same field-policy nilling as attributes. This issue affects ash: from 2.11.0-rc.0 before 3.33.4. ## Configurations Reachable only when an application uses `Ash.Policy.Authorizer` field policies to restrict a calculation or aggregate, and exposes filtering on it to an actor who is denied that field (for example an authenticated user filtering through AshGraphql or AshJsonApi).