CVE-2026-47072
MediumPublic exploitCRLF injection in WebSocket upgrade request in hackney
Published May 25, 2026 · Updated Oct 8, 2026 · Also known as EEF-CVE-2026-47072, EUVD-2026-31690, GHSA-f9vr-g2g2-x9fg
Key Facts
Routine patching- CVE-2026-47072 is a medium-severity vulnerability (CVSS 6.9 v4) affecting Hackney (Benoitc).
- It is not listed in any known-exploited vulnerabilities catalog. Public exploit code is available.
- EPSS estimates a 0.5% probability of exploitation in the next 30 days.
- Fixed versions are available, including Hackney 4.0.1, Hackney 52310ca807e7b48441ba0e9129171f535313fdd1.
- Brandefense priority: routine patching, as no exploitation is known and its severity is moderate or low.
CVSS v4
6.9
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS (30-day exploit likelihood)
0.5%
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2026-47072 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
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.
Affected Products
3 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| HackneyBenoitc | >= 2.0.0 | 4.0.1 |
Patched Releases
Hackney
4.0.1, 52310ca807e7b48441ba0e9129171f535313fdd1
Timeline
Publicly disclosed
May 25, 2026
Last updated
Oct 8, 2026
Weakness Type
- CWE-93 Improper Neutralization of CRLF Sequences ('CRLF Injection')
References
- advisoryGHSA advisory
- advisoryhttps://github.com/benoitc/hackney/security/advisories/GHSA-f9vr-g2g2-x9fg
- advisoryhttps://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47072.json
- advisoryhttps://nvd.nist.gov/vuln/detail/CVE-2026-47072
- patchhttps://github.com/benoitc/hackney/commit/52310ca807e7b48441ba0e9129171f535313fdd1
FAQ
Common Questions.
Improper Neutralization of CRLF Sequences ('CRLF Injection') vulnerability in benoitc hackney allows HTTP Request/Response Splitting.
Affected: Hackney (Benoitc) versions >= 2.0.0. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
Fixed versions are available, including Hackney 4.0.1, Hackney 52310ca807e7b48441ba0e9129171f535313fdd1.
Brandefense priority: routine patching, as no exploitation is known and its severity is moderate or low.
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