CVE-2026-77950 RPC error handler fails open in AshTypescript, disclosing unredacted errors
An unauthenticated attacker can trigger internal error messages containing sensitive data by causing an error shape mismatch in the RPC error handler.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-77950?
CVE-2026-77950 is a medium-severity vulnerability in ash-project ash_typescript, published on 1 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-209
Which versions are affected by CVE-2026-77950?
1 open source package ship an affected version, including ash_typescript.
| Package | Affected | Fixed in |
|---|---|---|
ash_typescript Hex | From 0.8.0 | 0.18.0 |
How do I fix CVE-2026-77950?
Upgrade ash_typescript to 0.18.0 or later.
Is CVE-2026-77950 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77950 exists.
Sources
Also known as EEF-CVE-2026-77950, GHSA-mjr7-r3rf-x963.