{"cve":"CVE-2026-33131","nvd":{"published":"2026-03-20T11:18:02.700","modified":"2026-06-17T10:36:59.997","status":"Analyzed","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","score":9.1},"cwes":["CWE-290"],"references":["https://github.com/h3js/h3/security/advisories/GHSA-3vj8-jmxq-cgj5"],"products":["h3:h3"],"source":"nvd","synced_at":"2026-10-19T22:26:19.218427112+00:00"},"epss":{"cve":"CVE-2026-33131","score":0.00395,"percentile":0.3372,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-3vj8-jmxq-cgj5","url":"https://osv.dev/vulnerability/GHSA-3vj8-jmxq-cgj5","summary":"h3 has a middleware bypass with one gadget","modified":"2026-03-20T21:59:20.258715Z","packages":[{"ecosystem":"npm","name":"h3","purl":"pkg:npm/h3","ranges":[">=2.0.0-0 <2.0.1-rc.15"],"fixed":["2.0.1-rc.15"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}