What’s Vulnerable › Vulnerabilities

CVE-2026-47067: Atom table exhaustion via unrecognized URL schemes in hackney

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-05-25 · updated 2026-07-24
• Weakness: CWE-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.

Affected products

• benoitc hackney: from 2.0.0 before 4.0.1 — fixed in 4.0.1

How to fix

Upgrade to a fixed version: benoitc hackney 4.0.1. Check the vendor advisory for mitigations.

References

• https://cna.erlef.org/cves/CVE-2026-47067.html
• https://github.com/benoitc/hackney/commit/31f6f0e27e096ad88743dfded4f030a3ee74972e
• https://github.com/benoitc/hackney/security/advisories/GHSA-9653-rcfr-5c62
• https://osv.dev/vulnerability/EEF-CVE-2026-47067
• https://github.com/benoitc/hackney/security/advisories/GHSA-9653-rcfr-5c62

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