CVE-2026-77856 Unbounded atom creation from typed struct field names in AshTypescript field selector
An unauthenticated attacker can crash the Elixir node by exhausting the atom table via crafted field names in AshTypescript.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-77856?
CVE-2026-77856 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 typed struct field names.
resolve_typed_struct_field/2 in lib/ash_typescript/rpc/field_processing/field_selector.ex looks a client-supplied field name up in the typed struct's reverse map and, when it finds no match, falls back to String.to_atom/1. Because this runs before any field-existence check, an unresolvable name mints a permanent atom rather than being rejected as unknown. Atoms are never garbage collected, so a request carrying many distinct names on a typed struct field grows the atom table until the VM aborts at its limit.
This issue affects ash_typescript: from 0.11.0 before 0.18.0.
Weakness: CWE-770
Which versions are affected by CVE-2026-77856?
1 open source package ship an affected version, including ash_typescript.
| Package | Affected | Fixed in |
|---|---|---|
ash_typescript Hex | From 0.11.0 | 0.18.0 |
How do I fix CVE-2026-77856?
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-2026-77856 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77856 exists.
Sources
Also known as EEF-CVE-2026-77856, GHSA-rj47-h936-4cxw.