EEF-CVE-2026-47067

Atom table exhaustion via unrecognized URL schemes in hackney

## Summary Allocation of Resources Without Limits or Throttling vulnerability in benoitc hackney allows Flooding. The URL parser in src/hackney\_url.erl converts every unrecognized URL scheme to a permanent BEAM atom via binary\_to\_atom/2. BEAM atoms are never garbage-collected and the atom table defaults to a hard limit of 1,048,576 entries. An attacker who can supply URLs with attacker-chosen scheme prefixes — directly as request targets, as configured webhook URLs, or via Location headers followed during redirects — can exhaust the atom table and crash the entire BEAM VM with system\_limit. This issue affects hackney: from 2.0.0 before 4.0.1.