Chained filter expressions against calculations and aggregates are not replaced with nil when subject to field‑policy restrictions, allowing an actor to perform a yes/no oracle that reveals the exact value. Because the nilling logic was only applied to attributes, a filter such as filter(secret_calc == "x") or filter(comment_count == n) caused the underlying calculation or aggregate to execute, leaking whether any records matched and thereby exposing the protected value one probe at a time.

The vulnerability exists in the Ash web framework for Elixir. It affects all releases from 2.11.0‑rc.0 up to, but not including, 3.33.4. The exposed surface includes endpoints that accept GraphQL or JSON API filter arguments, which are commonly exposed to lower‑privileged actors as the framework intends to protect them via field policies.

The CVSS score of 6.0 indicates a moderate severity exposure. EPSS data is not available, and the vulnerability is not listed in the CISA KEV catalog. Attackers can exploit the flaw by sending crafted filter arguments through the exposed API endpoints; no additional privileges or code execution are required. Once the attacker’s filtering succeeds, the result set size or presence reveals the secret value, effectively turning the filter into an oracle attack. The lack of a patch in the affected releases increases the window of vulnerability.