CVE-2026-47073
Received Received - Intake
Memory Exhaustion in hackney WebSocket Client

Publication date: 2026-05-25

Last updated on: 2026-05-25

Assigner: EEF

Description
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.
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Meta Information
Published
2026-05-25
Last Modified
2026-05-25
Generated
2026-05-26
AI Q&A
2026-05-26
EPSS Evaluated
N/A
NVD
CVE-2026-47073
EUVD
EUVD-2026-31694
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
benoitc hackney From 2.0.0 (inc) to 4.0.1 (exc)
Helpful Resources
Exploitability
CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-400 The product does not properly control the allocation and maintenance of a limited resource.
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability is an Allocation of Resources Without Limits or Throttling issue in the benoitc hackney WebSocket client. It allows an attacker controlling the WebSocket server to cause the client to consume unlimited memory, leading to a potential denial of service.

Specifically, there are three code paths where memory usage is unbounded: first, the handshake response accumulates bytes into a buffer without size limits; second, frame payload lengths are not validated against any maximum size, allowing very large frames to exhaust memory; third, continuation frames accumulate indefinitely if a final frame is never sent.

No authentication or special client configuration is needed by the attacker, only control of the WebSocket server the client connects to.


How can this vulnerability impact me? :

This vulnerability can lead to a denial of service condition by exhausting the memory of the client application using the hackney WebSocket client. An attacker controlling the WebSocket server can cause the client to consume excessive memory, potentially crashing the client or degrading its performance.


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0/70
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