CVE-2026-47073
Unbounded memory consumption in WebSocket client in hackney
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.
INFO
Published Date :
May 25, 2026, 3:16 p.m.
Last Modified :
May 27, 2026, 1:54 p.m.
Remotely Exploit :
Yes !
Source :
6b3ad84c-e1a6-4bf7-a703-f496b71e49db
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 4.0 | HIGH | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | ||||
| CVSS 4.0 | HIGH | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db |
Solution
- Update hackney to version 4.0.1 or later.
- Implement memory usage limits for WebSocket buffers.
- Validate declared frame payload lengths against a limit.
- Manage fragmentation buffers to prevent unbounded growth.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-47073.
| URL | Resource |
|---|---|
| https://cna.erlef.org/cves/CVE-2026-47073.html | Third Party Advisory Patch |
| https://github.com/benoitc/hackney/commit/ce0109e2970ace6e20ff29bae9d05c3ac22ec6dc | Patch |
| https://github.com/benoitc/hackney/security/advisories/GHSA-q8jg-fgj4-fphf | Exploit Vendor Advisory Patch |
| https://osv.dev/vulnerability/EEF-CVE-2026-47073 | Third Party Advisory Patch |
| https://github.com/benoitc/hackney/security/advisories/GHSA-q8jg-fgj4-fphf | Exploit Vendor Advisory Patch |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-47073 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-47073
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-47073 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-47073 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
May. 27, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CPE Configuration OR *cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:* versions from (including) 2.0.0 up to (excluding) 4.0.1 Added Reference Type EEF: https://cna.erlef.org/cves/CVE-2026-47073.html Types: Patch, Third Party Advisory Added Reference Type EEF: https://github.com/benoitc/hackney/commit/ce0109e2970ace6e20ff29bae9d05c3ac22ec6dc Types: Patch Added Reference Type CISA-ADP: https://github.com/benoitc/hackney/security/advisories/GHSA-q8jg-fgj4-fphf Types: Exploit, Patch, Vendor Advisory Added Reference Type EEF: https://github.com/benoitc/hackney/security/advisories/GHSA-q8jg-fgj4-fphf Types: Exploit, Patch, Vendor Advisory Added Reference Type EEF: https://osv.dev/vulnerability/EEF-CVE-2026-47073 Types: Patch, Third Party Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
May. 26, 2026
Action Type Old Value New Value Added Reference https://github.com/benoitc/hackney/security/advisories/GHSA-q8jg-fgj4-fphf -
New CVE Received by 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
May. 25, 2026
Action Type Old Value New Value Added 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. Added CVSS V4.0 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 Added CWE CWE-400 Added Reference https://cna.erlef.org/cves/CVE-2026-47073.html Added Reference https://github.com/benoitc/hackney/commit/ce0109e2970ace6e20ff29bae9d05c3ac22ec6dc Added Reference https://github.com/benoitc/hackney/security/advisories/GHSA-q8jg-fgj4-fphf Added Reference https://osv.dev/vulnerability/EEF-CVE-2026-47073