CVE-2026-47067

Atom table exhaustion via unrecognized URL schemes in hackney

At a glance

Severity: HIGH 8.7
EPSS: EPSS 0.75 % · percentile 55 (2026-10-27)
State: PUBLISHED
Published: 2026-05-25
Updated: 2026-05-27
Assigner: EEF
NVD status: Analyzed

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.

Scores

Version	Score	Vector	Scored by
CVSS 4.0	HIGH 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	EEF
CVSS 4.0	HIGH 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	NVD · 6b3ad84c-e1a6-4bf7-a703-f496b71e49db (Secondary)
CVSS 3.1	HIGH 7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	NVD · nvd@nist.gov (Primary)

Weaknesses (CWE)

CWE-770

European references

ENISA EUVD · EUVD-2026-31691
GCVE · GCVE-0-2026-47067

Affected configurations (NVD CPE)

cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:* ≥ 2.0.0 < 4.0.1

Affected products

Product	Versions
benoitc · hackney	affected 2.0.0 < 4.0.1
benoitc · hackney	affected d9713695c0d99855d12c73fd8a0b4be0543950c4 < 31f6f0e27e096ad88743dfded4f030a3ee74972e

References

Sources

Source	Licence
CVE List (CVEProject cvelistV5)	CVE Program Terms of Use
EPSS (FIRST.org)	FIRST — attribution requested
ENISA EUVD	ENISA — reproduction authorised, source acknowledged
NVD (NIST) via fkie-cad/nvd-json-data-feeds	Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD