# 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.

- **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 1 Sep 2026
- **Updated:** 1 Sep 2026
- **Also known as:** EEF-CVE-2026-77950, GHSA-mjr7-r3rf-x963

## 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 (Generation of Error Message Containing Sensitive Information)

## Which versions are affected by CVE-2026-77950?

1 open source package ship an affected version, including ash_typescript.


| Package | Ecosystem | 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-77950 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77950 exists.

Affected packages and fixed versions:
- ash_typescript (Hex): affected from 0.8.0; fixed in 0.18.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-77950/ (Markdown: https://insights.sbomify.com/CVE-2026-77950/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-77950
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-77950
- OSV: https://osv.dev/vulnerability/CVE-2026-77950

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-77950/
Summaries are generated and may contain mistakes; the official description above is the record.