CRLF Injection Affecting h3 package, versions <1.15.9>=2.0.0-beta.0 <2.0.1-rc.17
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-JS-H3-15746329
- published22 Mar 2026
- disclosed20 Mar 2026
- creditrestriction
Introduced: 20 Mar 2026
CVE-2026-86252 (opens in a new tab)How to fix?
Upgrade h3 to version 1.15.9, 2.0.1-rc.17 or higher.
Overview
h3 is a Minimal H(TTP) framework built for high performance and portability.
Affected versions of this package are vulnerable to CRLF Injection via unsanitized carriage return characters in the data and comment fields of the EventStream class. An attacker can inject arbitrary server-sent events, spoof event types, and split a single event into multiple browser-parsed events by supplying specially crafted input containing carriage return characters.