Infinite loop 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-16876609
- published26 May 2026
- disclosed25 May 2026
- creditPJUllrich
Introduced: 25 May 2026
NewCVE-2026-47066 (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 Infinite loop through the parse_entries/2 function in the Alt-Svc parser. An attacker can pin a scheduler at 100% CPU by sending an Alt-Svc response header whose first entry starts with a non-token byte such as !, @, =, ;, or .. The parser recurses on the same bytes without making progress, so a single malicious header from an attacker-controlled origin can hang the connection process and prevent normal request handling.