CRLF Injection Affecting hackney package, versions >=2.0.0-beta.1 <4.0.1
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-HEX-HACKNEY-16877831
- published26 May 2026
- disclosed25 May 2026
- creditPJUllrich
Introduced: 25 May 2026
NewCVE-2026-47072 (opens in a new tab)How to fix?
Upgrade hackney to version 4.0.1 or higher.
Overview
Affected versions of this package are vulnerable to CRLF Injection in the do_handshake/1 WebSocket upgrade request assembly in the WebSocket client code. An attacker can inject extra header lines or rewrite the request line by supplying a path, sub-protocol, or extra header value containing \r, \n, or NUL. This lets a malicious caller smuggle attacker-controlled headers onto the wire during the upgrade request, which can corrupt the handshake and expose downstream services to request manipulation.