Executive brief
Ash is a framework for building Elixir applications. A security flaw was found where 'private' arguments—data intended to be set only by the server—can be manipulated by end-users. If an application uses these private arguments for critical tasks like verifying a user's identity or determining who owns a record, an attacker could potentially bypass security rules or modify data they shouldn't have access to.
Technical details
A vulnerability exists in the Ash framework's changeset building process where private action arguments (defined with 'public?: false') are not consistently stripped from untrusted input. In the standard changeset path (for_create, for_update, for_destroy), the filtering logic fails when parameter keys are provided as strings (binaries) rather than atoms, which is the default for user-supplied data. Additionally, the atomic and bulk update paths (fully_atomic_changeset/4) fail to strip private arguments entirely. An attacker can exploit this to inject values into arguments intended for internal server-side use, such as 'acting_user_id', leading to privilege escalation or integrity violations. The issue is fixed in version 3.29.3.
Affected products
- ash-project ash >= 3.0.0, < 3.29.3
Timeline
- 2026-06-23: advisory: Advisory published by GitHub and Erlang Ecosystem Foundation
- 2026-06-23: patched: Fix committed to ash-project/ash repository