CVE-2026-47072
HighSummary
The CRLF Injection vulnerability in the hackney library allows for HTTP Request/Response Splitting. An attacker can inject arbitrary HTTP headers into the outbound WebSocket upgrade request, leading to various threats such as credential spoofing or malicious request forwarding.
Risk Assessment
Organizations may be exposed to header spoofing attacks, which can lead to data leakage or session manipulation. Additionally, this could result in malicious log and cache poisoning.
Recommendation
It is recommended to update the hackney library to version 4.0.1 or later to mitigate this vulnerability. A code audit should also be conducted to identify and secure areas where CRLF injections may occur.
Original NVD description (English source)
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.