CRLF Injection Affecting hackney package, versions <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-17111516
- published31 May 2026
- disclosed25 May 2026
- creditPJUllrich
Introduced: 25 May 2026
NewCVE-2026-47069 (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 via the setcookie/3 function in the cookie header builder. An attacker can inject a second Set-Cookie header by supplying a crafted domain or path value through request-derived input such as the Host header, request path, or tenant configuration. This lets the attacker set arbitrary cookies in the victim’s browser, enabling session fixation or other cookie-based abuse against users of applications that pass untrusted data into cookie options.