H3 is a minimal H(TTP) framework. Versions 2.0.0-0 through 2.0.1-rc.14 contain a Host header spoofing vulnerability in the NodeRequestUrl (which extends FastURL) which allows middleware bypass. When event.url, event.url.hostname, or event.url._url is accessed, such as in a logging middleware, the _url getter constructs a URL from untrusted data, including the user-controlled Host header. Because H3's router resolves the route handler before middleware runs, an attacker can supply a crafted Host header (e.g., Host: localhost:3000/abchehe?) to make the middleware path check fail while the route handler still matches, effectively bypassing authentication or authorization middleware. This affects any application built on H3 (including Nitro/Nuxt) that accesses event.url properties in middleware guarding sensitive routes. The issue requires an immediate fix to prevent FastURL.href from being constructed with unsanitized, attacker-controlled input. Version 2.0.1-rc.15 contains a patch for this issue.
References
| Link | Resource |
|---|---|
| https://github.com/h3js/h3/security/advisories/GHSA-3vj8-jmxq-cgj5 | Exploit Vendor Advisory |
Configurations
Configuration 1 (hide)
|
History
No history.
Information
Published : 2026-03-20 11:18
Updated : 2026-03-20 19:45
NVD link : CVE-2026-33131
Mitre link : CVE-2026-33131
CVE.ORG link : CVE-2026-33131
JSON object : View
Products Affected
h3
- h3
CWE
CWE-290
Authentication Bypass by Spoofing
