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Description

Improper Neutralization of CRLF Sequences vulnerability in benoitc hackney allows HTTP Request Splitting. 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 before 4.0.1.

PUBLISHED Reserved 2026-05-18 | Published 2026-05-25 | Updated 2026-05-27 | Assigner EEF




MEDIUM: 6.8CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N

Problem types

CWE-93 Improper Neutralization of CRLF Sequences ('CRLF Injection')

Product status

Default status
unaffected

Any version before 4.0.1
affected

Default status
unaffected

8bb1a359a81ae58567c84f8d24564e9742e6f2bd (git) before ca73dd0aba0ed557449c18288bf07241671a43c9
affected

Credits

tepel-chen finder

Benoit Chesneau remediation developer

Jonatan Männchen / EEF analyst

References

github.com/...ackney/security/advisories/GHSA-j9wq-vxxc-94wf exploit

github.com/...ackney/security/advisories/GHSA-j9wq-vxxc-94wf vendor-advisory related

cna.erlef.org/cves/CVE-2026-47075.html related

osv.dev/vulnerability/EEF-CVE-2026-47075 related

github.com/...ommit/ca73dd0aba0ed557449c18288bf07241671a43c9 patch

cve.org (CVE-2026-47075)

nvd.nist.gov (CVE-2026-47075)

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