CVE-2026-47077Public exploitNetwork attack vector

Denial of service via unbounded HTTP/3 buffering

Published May 25, 2026 · Updated May 25, 2026

Resource exhaustion in hackney 2.0.0 through 4.0.0 allows remote attackers controlling an HTTP/3 server to crash the BEAM runtime. hackney_h3:await_response_loop/6 appends every response chunk to an uncapped binary while each incoming message restarts its inactivity timer. Exposure requires explicit HTTP/3 transport use; the default TCP/TLS transport is unaffected, and sustained chunks can exhaust process or host memory.

CVSS severity8.2
High
EPSS probability0.70%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in hackney 2.0.0 through 4.0.0 allows remote attackers controlling an HTTP/3 server to crash the BEAM runtime. hackney_h3:await_response_loop/6 appends every response chunk to an uncapped binary while each incoming message restarts its inactivity timer. Exposure requires explicit HTTP/3 transport use; the default TCP/TLS transport is unaffected, and sustained chunks can exhaust process or host memory.

The record

CVE
CVE-2026-47077
Published
May 25, 2026
Updated
May 25, 2026
Vendor
Benoit Chesneau
Product
Hackney
Classifications
CWE-400, CAPEC-125, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 25, 2026CVE publishedPublication date reported by the CVE source.
  2. May 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0334af206d5099fdf510ed9eda18e34396f065ad <3d25f9fea26c90609de9d64366fedfe5065413bc
  2. Affected versionversion=2.0.0 <4.0.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Benoit Chesneau · Hackneyversion=0334af206d5099fdf510ed9eda18e34396f065ad <3d25f9fea26c90609de9d64366fedfe5065413bc; version=2.0.0 <4.0.1

Published CVSS scores

7.5NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.2Erlang Ecosystem FoundationCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
CAPEC-125Flooding
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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