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Fencer Vulns
high 8.7

CVE-2026-74837 json

Unbounded atom creation from client-supplied RPC field names in AshTypescript field formatter

published 2026-09-01 2 mo ago modified 2026-09-08 2 mo ago also EEF-CVE-2026-74837 , EUVD-2026-68929 , GHSA-mhxc-mhqx-3v28

cvss
8.7
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 46%
public exploits
0
none known

Summary

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.

Patch / fix

  • hex ash_typescript 0.18.0
  • ash-project ash_typescript 0.18.0

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
2 mo ago

Exploit prediction

0.55% chance of exploitation in the next 30 days, higher than 46% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/ash-project/ash_typescript/security/advisories/GHSA-mhxc-mhqx-3v28 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 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
CNA 4.0 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected packages

ecosystem package affected fixed in
hex ash_typescript
>=0.1.0, <0.18.0
0.18.0

Affected products

  • ash-project ash_typescript

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.