User Impersonation Affecting h3 package, versions >=2.0.0-beta.0 <2.0.1-rc.15
Threat Intelligence
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-H3-15692484
- published19 Mar 2026
- disclosed18 Mar 2026
- credithibwyli
Introduced: 18 Mar 2026
CVE-2026-33131 (opens in a new tab)How to fix?
Upgrade h3 to version 2.0.1-rc.15 or higher.
Overview
h3 is a Minimal H(TTP) framework built for high performance and portability.
Affected versions of this package are vulnerable to User Impersonation via manipulation of the Host header in HTTP requests, which allows untrusted input to influence the construction of the event.url object. An attacker can bypass middleware protections by crafting requests that spoof the URL, causing the middleware to be bypassed and unauthorized access to protected endpoints.