TI-2026-34669 Aliases CVE-2026-47067 GHSA-9653-rcfr-5c62

Atom table exhaustion via unrecognized URL schemes in hackney

HIGH 77CWE-770Published 2026-05-25 · Updated 2026-05-27

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Attack requirements: None
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · High
Fix status: Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-770.

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00753 55th percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix Fixed hackney (benoitc): 4.0.1hackney (Hex): 4.0.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: Yes
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
benoitc	hackney	2.0.0 to before 4.0.1	4.0.1	Patch available	CNA
—	hackney (Hex)	2.0.0 to before 4.0.1	4.0.1	Patch available	GHSA-9653-rcfr-5c62

hackney Vendorbenoitc Affected 2.0.0 to before 4.0.1 Fixed in 4.0.1 Patch available CNA
hackney (Hex) Vendor— Affected 2.0.0 to before 4.0.1 Fixed in 4.0.1 Patch available GHSA-9653-rcfr-5c62

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:benoitc:hackney::::::::	2.0.0 to before 4.0.1	Vulnerable	benoitc

cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:* Versions 2.0.0 to before 4.0.1 Vulnerable ·benoitc

Remediation

Fix · CNA hackney (benoitc) Fixed in 4.0.1
Fix · GHSA-9653-rcfr-5c62 hackney (Hex) Fixed in 4.0.1 Advisory →

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

Release · 2026-05-25
benoitc hackney 4.0.1
10 records Highest priority Priority HIGH 6 HIGH, 4 MEDIUM
Other records, highest priority first
- TI-2026-34675 Unbounded memory consumption in WebSocket client in hackneyPriority HIGH 77
- TI-2026-34668 Infinite loop in Alt-Svc header parser in hackneyPriority HIGH 77
- TI-2026-34679 Unbounded body accumulation in HTTP/3 response loop in hackneyPriority HIGH 75
Show all 10 records →

Timeline

2026-10-02 Threatist record created from CVE-2026-47067
2026-10-03 Alias added: GHSA-9653-rcfr-5c62

References

Exploit 1

https://github.com/benoitc/hackney/security/advisories/GHSA-9653-rcfr-5c62

Patch 3

Advisory 1

https://nvd.nist.gov/vuln/detail/CVE-2026-47067

Other 1

https://github.com/benoitc/hackney

TI-2026-34675 Unbounded memory consumption in WebSocket client in hackney CVSS 4.0HIGH 8.7
TI-2026-34668 Infinite loop in Alt-Svc header parser in hackney CVSS 4.0HIGH 8.7
TI-2026-34679 Unbounded body accumulation in HTTP/3 response loop in hackney CVSS 4.0HIGH 8.2
TI-2026-34673 SOCKS5 TLS upgrade ignores caller timeout in hackney CVSS 4.0HIGH 8.2
TI-2026-34674 CRLF injection in WebSocket upgrade request in hackney CVSS 4.0MEDIUM 6.9
TI-2026-34678 SSRF allowlist bypass via percent-encoded host in hackney CVSS 4.0MEDIUM 6.9

See all 9 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences