# CVE-2026-74837: Unbounded atom creation from client-supplied RPC field names in AshTypescript field formatter

> An unauthenticated attacker can crash the Elixir node by sending RPC requests with unique field names, exhausting the BEAM atom table.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/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-2026-74837, GHSA-mhxc-mhqx-3v28

## What is CVE-2026-74837?

CVE-2026-74837 is a high-severity denial of service 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

Allocation of Resources Without Limits or Throttling vulnerability in ash-project ash_typescript allows an unauthenticated attacker to exhaust the BEAM atom table and abort the node via client-supplied RPC field names.

AshTypescript.FieldFormatter.convert_to_field_atom/2 in lib/ash_typescript/field_formatter.ex converts a client-supplied field name to an atom with String.to_atom/1 when no matching atom already exists. It delegates first to parse_input_field/2, which resolves the name with String.to_existing_atom/1 and falls back to returning the plain string; convert_to_field_atom/2 then mints an atom from that string rather than treating the name as unknown.

RPC field selection reaches it for every requested field name through AshTypescript.Rpc.FieldProcessing.FieldSelector, which resolves each name before checking that the field exists, with no allowlist, length bound, or rate limit. Atoms are never garbage collected, so each distinct name mints a permanent one and the VM aborts once the atom table limit is reached. A field name over 255 characters additionally raises an uncaught SystemLimitError.

This issue affects ash_typescript: from 0.1.0 before 0.18.0.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2026-74837?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `ash_typescript` | Hex | From 0.1.0 | 0.18.0 |

## How do I fix CVE-2026-74837?

Upgrade ash_typescript to 0.18.0 or later.

## Is CVE-2026-74837 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-74837 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74837 and fix it if it is affected.

What it is: CVE-2026-74837 is a high-severity denial of service 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-2026-74837 exists.

Affected packages and fixed versions:
- ash_typescript (Hex): affected from 0.1.0; 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-2026-74837/ (Markdown: https://insights.sbomify.com/CVE-2026-74837/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74837
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74837
- OSV: https://osv.dev/vulnerability/CVE-2026-74837

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74837/
Summaries are generated and may contain mistakes; the official description above is the record.