PT-2026-43069 · Benoitc · Hackney

Benoit Chesneau + 2 · Published 2026-05-25 · Updated 2026-05-25 · CVE-2026-47072

Mitre

CVSS v4.0

6.9

Medium

Base vector

AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:H/SA:N

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.

Fix

Weakness Enumeration

CWE-93

Related Identifiers

CVE-2026-47072

Affected Products

Hackney

References · 4

• https://github.com/benoitc/hackney/commit/52310ca807e7b48441ba0e9129171f535313fdd1 · Patch
• https://github.com/benoitc/hackney/security/advisories/GHSA-f9vr-g2g2-x9fg · Vendor Advisory
• https://cna.erlef.org/cves/CVE-2026-47072.html · Note
• https://osv.dev/vulnerability/EEF-CVE-2026-47072 · Note