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CVE-2026-47067

Atom table exhaustion via unrecognized URL schemes in hackney

Published: May 25, 2026Updated: May 27, 2026 Sources: CVE List NVDCWE-770

Description

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.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High

Weaknesses

Affected Products

benoitcoss-projectOSS Librariesaka benoitc/gunicorn, hackney, gunicorn

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

1 technique
Impact
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References

and 1 more references View all →

Timeline

Published
May 25, 2026
Last Updated
May 27, 2026

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