CVE-2026-47072
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk42th percentile - higher than 42% of all known CVEs
Summary
CRLF Injection vulnerability in the hackney library allows an attacker to inject arbitrary HTTP headers into a WebSocket request. Lack of CRLF and NUL filtering at four injection points enables request manipulation, potentially leading to credential spoofing, cache poisoning, or request smuggling via proxies.
Risk Assessment
An attacker can hijack WebSocket communication by impersonating the target server, threatening the confidentiality and integrity of data transmitted by the application.
Recommendation
Immediately upgrade the hackney library to version 4.0.1 or later, which includes a fix for this vulnerability.
Other vulnerabilities in hackney
See all- CVE-2026-47077High
A vulnerability in the hackney library (versions 2.0.0 through 4.0.1) allows a Flooding attack due to missing size limits on the HTTP/3 response buffer. A malicious server can send small chunks, resetting the timeout, leading to unbounded memory growth and exhaustion of the BEAM process heap.
- CVE-2026-47076Medium
The hackney library for Erlang/OTP versions 0.13.0 through 4.0.1 contains a Server-Side Request Forgery (SSRF) vulnerability due to an interpretation conflict. The URL normalizer decodes the host after validation, allowing bypass of allowlists and access to internal IP addresses (e.g., 127.0.0.1, 169.254.169.254).
- CVE-2026-47075High
hackney before version 4.0.1 does not percent-encode CR (\r) and LF (\n) characters in the URL query component, enabling HTTP Request Splitting. An attacker controlling the URL can inject raw CRLF sequences into the query string, allowing arbitrary HTTP headers or request splitting.
- CVE-2026-47073High
A vulnerability in the hackney library (versions 2.0.0 through 4.0.1) allows memory exhaustion by an attacker-controlled WebSocket server. The WebSocket client does not limit buffer sizes in three code paths, enabling a Flooding attack.
- CVE-2026-47071High
The hackney library versions 0.10.0 up to (but not including) 4.0.1 contains an uncontrolled resource consumption vulnerability in the SOCKS5 transport. After SOCKS5 negotiation, the connection is upgraded to TLS with an infinite timeout, allowing a malicious proxy to block the process indefinitely.
- CVE-2026-47070Medium
The hackney library versions 3.1.1 before 4.0.1 is vulnerable to sensitive data exposure. The HTTP/3 module (hackney_h3.erl) does not perform cross-origin checks on redirects, causing authorization headers and cookies to be sent to foreign hosts.
- CVE-2026-47069Medium
A CRLF Injection vulnerability was found in the hackney library (versions from 0.9.0 before 4.0.1) in the hackney_cookie:setcookie/3 function. An attacker controlling the domain or path option can inject a CRLF sequence and arbitrary Set-Cookie headers, leading to HTTP Response Splitting.
- CVE-2026-47067High
The hackney library versions 2.0.0 up to (but not including) 4.0.1 contains a vulnerability that exhausts the BEAM atom table. The URL parser converts unrecognized URL schemes to atoms via binary_to_atom/2, which are never garbage-collected. An attacker can supply many URLs with unique schemes, exceeding the atom table limit and crashing the entire BEAM VM.
- CVE-2026-47066High
The hackney library versions 2.0.0-beta.1 up to (but not including) 4.0.1 contains an infinite loop vulnerability in the Alt-Svc header parser. The parse_token/2 function does not guarantee forward progress for certain bytes, leading to a recursive loop consuming 100% CPU. An Alt-Svc: ! header is sufficient to trigger the vulnerability.
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.