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TI-2026-34674 Aliases CVE-2026-47072GHSA-f9vr-g2g2-x9fg

CRLF injection in WebSocket upgrade request in hackney

Priority HIGH 70CWE-93Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
Present
Impact type
—
Confidentiality · integrity · availability
None · Low · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub.

Summary

Improper Neutralization of CRLF Sequences ('CRLF Injection') vulnerability in benoitc hackney allows HTTP Request/Response Splitting. The WebSocket upgrade code in src/hackney_ws.erl copies the host, path, headers (ExtraHeaders), and protocols options from the caller-supplied opts map into the internal #ws_data{} record in init/1 and then splices them verbatim into the raw HTTP/1.1 upgrade request by binary concatenation in do_handshake/1. No CRLF or NUL stripping is performed at any of these four injection sites. An attacker who controls any of these options — for example by forwarding URL components or header values from untrusted input into hackney_ws:start_link/1 — can inject arbitrary HTTP headers into the outbound WebSocket upgrade request, leading to header injection, credential spoofing toward the upstream server, log and cache poisoning, or request smuggling via intermediary proxies. This issue affects hackney: from 2.0.0 before 4.0.1.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00542 45th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed hackney (benoitc): 4.0.1hackney (Hex): 4.0.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
benoitchackney2.0.0 to before 4.0.14.0.1Patch availableCNA
—hackney (Hex)2.0.0 to before 4.0.14.0.1Patch availableGHSA-f9vr-g2g2-x9fg
  • hackney Vendorbenoitc Affected 2.0.0 to before 4.0.1 Fixed in 4.0.1 Patch available CNA
  • hackney (Hex) Vendor— Affected 2.0.0 to before 4.0.1 Fixed in 4.0.1 Patch available GHSA-f9vr-g2g2-x9fg

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*2.0.0 to before 4.0.1Vulnerablebenoitc
  • cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:* Versions 2.0.0 to before 4.0.1 Vulnerable ·benoitc

Remediation

  • Fix · CNA hackney (benoitc) Fixed in 4.0.1
  • Fix · GHSA-f9vr-g2g2-x9fg hackney (Hex) Fixed in 4.0.1 Advisory →

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    benoitc hackney 4.0.1

    10 records Highest priority Priority HIGH 6 HIGH, 4 MEDIUM

    Other records, highest priority first

    • TI-2026-34675 Unbounded memory consumption in WebSocket client in hackneyPriority HIGH 77
    • TI-2026-34669 Atom table exhaustion via unrecognized URL schemes in hackneyPriority HIGH 77
    • TI-2026-34668 Infinite loop in Alt-Svc header parser in hackneyPriority HIGH 77
    Show all 10 records →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-47072
  2. 2026-10-03 Alias added: GHSA-f9vr-g2g2-x9fg

References

Exploit 1

Patch 3

Advisory 1

Other 1

  • TI-2026-34675 Unbounded memory consumption in WebSocket client in hackney CVSS 4.0HIGH 8.7
  • TI-2026-34669 Atom table exhaustion via unrecognized URL schemes in hackney CVSS 4.0HIGH 8.7
  • TI-2026-34668 Infinite loop in Alt-Svc header parser in hackney CVSS 4.0HIGH 8.7
  • TI-2026-34679 Unbounded body accumulation in HTTP/3 response loop in hackney CVSS 4.0HIGH 8.2
  • TI-2026-34673 SOCKS5 TLS upgrade ignores caller timeout in hackney CVSS 4.0HIGH 8.2
  • TI-2026-34678 SSRF allowlist bypass via percent-encoded host in hackney CVSS 4.0MEDIUM 6.9
See all 9 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences