Am I affected?
Description
Incorrect Authorization vulnerability in ash-project ash_typescript allows an unauthorized RPC caller to read attribute values that Ash field policies denied.
When a field policy denies an attribute, Ash substitutes %Ash.ForbiddenField{}, which retains the real value in original_value because embedded resources must remain writable, and hides it from Inspect rather than removing it. AshTypescript.Rpc.ResultProcessor strips these markers to nil on its template-driven paths, but normalize_primitive/1 in lib/ash_typescript/rpc/result_processor.ex had no such clause, so a marker fell through to the generic struct branch which calls Map.from_struct/1 and serializes every key, original_value included. The denied value is returned to the caller inside the marker that represents its own denial.
The simplest trigger is an action returning an embedded resource as a map, which routes through normalize_resource_struct/2 with an empty template. normalize_value_for_json/1 is a public, unguarded entry point to the same path.
This issue affects ash_typescript: from 0.11.0 before 0.18.0.
Weaknesses & attack patterns
Weakness
CWE-863
·
Incorrect Authorization
in catalog →
MITRE ↗
Attack patterns
CAPEC-122
·
Privilege Abuse
MITRE ↗
Affected — Hex / ash_typescript Hex.pm ↗ Repository ↗
modules · source files · routines
Affected — GitHub / ash-project/ash_typescript Repository ↗
modules · source files · routines
Configurations
The application exposes an AshTypescript RPC endpoint over HTTP and relies on Ash field policies to hide attributes on embedded resources that an action returns as a map.
References
Credits
CVSS breakdown
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N