EEF-CVE-2026-77950

## Summary

Generation of Error Message Containing Sensitive Information vulnerability in ash-project ash\_typescript allows an unauthenticated attacker to receive unredacted internal error data by provoking an error shape the configured error handler does not match.

apply\_error\_handler/3 in lib/ash\_typescript/rpc/errors.ex is the only hook an application has for redacting or suppressing errors before they reach the client, with a nil return dropping the error entirely. Its rescue clause logs a warning and then returns the original, pre-handler error map. Error handlers are conventionally written as pattern-matching functions over expected error shapes, so an unmatched shape raises FunctionClauseError and the raw transformed error, including any secrets carried in vars, is emitted instead. An intent to suppress an error becomes an intent to publish it. The rescue catches exceptions only, so a handler that throws or exits still propagates.

This issue affects ash\_typescript: from 0.8.0 before 0.18.0.

## Configuration

The application exposes an AshTypescript RPC endpoint over HTTP and configures a custom error\_handler in its typescript\_rpc domain section for redaction or suppression.