CVE-2026-47072Public exploitNetwork attack vector

Header injection via unsanitized WebSocket upgrade fields

Published May 25, 2026 · Updated May 25, 2026

CRLF injection in hackney 2.0.0 through 4.0.0 allows context-dependent attackers to alter outbound WebSocket upgrade requests. The do_handshake/1 function concatenates caller-controlled path and header fields into the raw request without rejecting CR, LF, or NUL bytes. Exploitation requires a consuming application to pass attacker-controlled options, enabling forged upstream headers, cache or log poisoning, or request smuggling.

CVSS severity6.9
Medium
EPSS probability0.54%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

CRLF injection in hackney 2.0.0 through 4.0.0 allows context-dependent attackers to alter outbound WebSocket upgrade requests. The do_handshake/1 function concatenates caller-controlled path and header fields into the raw request without rejecting CR, LF, or NUL bytes. Exploitation requires a consuming application to pass attacker-controlled options, enabling forged upstream headers, cache or log poisoning, or request smuggling.

The record

CVE
CVE-2026-47072
Published
May 25, 2026
Updated
May 25, 2026
Vendor
Benoit Chesneau
Product
Hackney
Classifications
CWE-93
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=2.0.0 <4.0.1
  2. Affected versionversion=690cecaf236fba49526da404a5bc889a24367a3e <52310ca807e7b48441ba0e9129171f535313fdd1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Benoit Chesneau · Hackneyversion=2.0.0 <4.0.1; version=690cecaf236fba49526da404a5bc889a24367a3e <52310ca807e7b48441ba0e9129171f535313fdd1

Published CVSS scores

6.9Erlang Ecosystem FoundationCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:H/SA:N
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A: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-93Improper Neutralization of CRLF Sequences ('CRLF Injection')

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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