CVE-2026-82739: Ash.Resource.Validation.Confirm leaks a confirmed field's stored value in the atomic mismatch error

Generation of Error Message Containing Sensitive Information vulnerability in ash-project ash discloses the stored value of a confirmed field to an actor who fails its confirmation check.

Ash.Resource.Validation.Confirm's atomic implementation (atomic/2 in lib/ash/resource/validation/confirm.ex) built the mismatch error with its value set to the field being confirmed. When the actor supplies only the confirmation argument and not the field itself, value resolves through atomicref/2 to the field's current stored value, so the mismatch error echoes that stored value back to the actor. Against a confirmation guarding a sensitive attribute, an actor can submit a deliberately wrong confirmation and read the real value from the returned error. The fix reports the actor-supplied confirmation in the error instead of the stored field value.

This issue affects ash: from 2.17.20 before 3.32.2.