Executive brief
ash_typescript is a TypeScript integration library for Ash, a data-driven framework used to build APIs and web applications. A flaw in the RPC result processor fails to properly hide field values that have been restricted by access policies, allowing an unauthorized caller to read sensitive attributes that should have been denied. This could expose confidential data such as personal information, internal identifiers, or other sensitive fields that administrators intended to restrict.
Technical details
This is an authorization bypass vulnerability in ash_typescript's RPC layer. When a field policy denies access to an attribute, Ash wraps it in a %Ash.ForbiddenField{} marker that preserves the real value in an original_value key for internal use while hiding it from inspection. The normalize_primitive/1 function in lib/ash_typescript/rpc/result_processor.ex lacks a clause to strip these markers, causing the generic struct-to-map serialization path to call Map.from_struct/1, which serializes all keys including original_value. An unauthenticated RPC caller can trigger this by requesting an action that returns an embedded resource as a map, or by directly calling the public normalize_value_for_json/1 entry point. The issue affects ash_typescript versions 0.11.0 through 0.17.x; version 0.18.0 and later contain the fix.
Affected products
- ash-project ash_typescript 0.11.0 to 0.17.x
Timeline
- 2026-09-01: disclosed: CVE-2026-82730 published