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.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74837?
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
Which versions are affected by CVE-2026-74837?
1 open source package ship an affected version, including ash_typescript.
| Package | 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.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-74837 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-74837 exists.
Sources
Also known as EEF-CVE-2026-74837, GHSA-mhxc-mhqx-3v28.