Am I affected?
Description
hackney does not percent-encode carriage return (\r) or line feed (\n) characters in the URL query component before constructing the HTTP/1.1 request target. Characters outside the grammar defined in RFC 3986 Section 3.4 must be percent-encoded, but hackney_url:make_url/3 passes the query binary directly without validation or escaping. An attacker who can control all or part of a URL passed to hackney can inject raw CRLF sequences into the query string, which are then sent as HTTP line breaks in the request target. This enables injection of arbitrary HTTP headers or splitting of the HTTP request.
This issue affects hackney: from 0.13.1 before 4.0.1.
Weaknesses & attack patterns
Weakness
CWE-93
·
Improper Neutralization of CRLF Sequences ('CRLF Injection')
in catalog →
MITRE ↗
Attack patterns
CAPEC-105
·
HTTP Request Splitting
MITRE ↗
Affected — Hex / hackney Hex.pm ↗ Repository ↗
modules · source files · routines
Affected — GitHub / benoitc/hackney Repository ↗
modules · source files · routines
References
GHSA-j9wq-vxxc-94wf ↗
vendor-advisory
EEF-CVE-2026-47075 ↗
related
Credits
CVSS breakdown
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N