CVE-2026-47073

What it is

Allocation of Resources Without Limits or Throttling vulnerability in benoitc hackney allows Flooding. The WebSocket client in src/hackney_ws.erl imposes no upper bound on memory consumption in three code paths. First, read_handshake_response/3 accumulates received bytes into a growing buffer with no size cap; the per-receive timeout resets on every chunk, so a server that streams bytes without ever sending \r\n\r\n causes the buffer to grow until memory is exhausted. Second, parse_payload/9 and parse_active_payload/8 do not validate the declared frame payload length against any limit; because RFC 6455 allows payload lengths up to 2^63-1 bytes, a server that announces a very large frame and dribbles bytes causes the accumulation buffer to grow until OOM. Third, the frag_buffer field in #ws_data{} accumulates continuation frames indefinitely; a server that sends an endless stream of non-final (nofin) fragmented frames without ever sending a final (fin) frame grows frag_buffer without bound. In all three cases the attacker only needs to control the WebSocket server the hackney client connects to, with no authentication or special client configuration required. This issue affects hackney: from 2.0.0 before 4.0.1.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of service disruption.

Exploit odds

0.9% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-05-25 15:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-07-24 10:10 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.9% in the next 30 days (EPSS).
• Severity: 8.7 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-05-25 15:16 UTC

Last modified

2026-07-24 10:10 UTC

Exploit probability

0.9% · EPSS, next 30 days

Weakness

CWE-400 · Uncontrolled resource consumption

Record status

Analyzed

Affected

• Benoitc Hackney < 4.0.1

Attack profile CVSS 4.0 · 8.7

Attack vector

Network

Complexity

Low

Attack requirements

None

Privileges needed

None

User interaction

None

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

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Read https://cve-list.com/agent/cve/CVE-2026-47073.md and follow it. Check whether this project is affected by CVE-2026-47073. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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