{"id":"CVE-2026-33131","summary":"h3 has a middleware bypass with one gadget","details":"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.","aliases":["GHSA-3vj8-jmxq-cgj5"],"modified":"2026-08-12T03:51:31.601446198Z","published":"2026-03-20T10:16:29.556Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33131.json","cna_assigner":"GitHub_M","cwe_ids":["CWE-290"]},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33131.json"},{"type":"ADVISORY","url":"https://github.com/h3js/h3/security/advisories/GHSA-3vj8-jmxq-cgj5"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-33131"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/h3js/h3","events":[{"introduced":"0"},{"fixed":"91361835657410605f2041762da9e3f60d24ecfb"}],"database_specific":{"extracted_events":[{"introduced":"2.0.0-0"},{"fixed":"2.0.1-rc.15"},{"fixed":"2.0.1-rc.14"}],"source":["AFFECTED_FIELD","DESCRIPTION"]}}],"versions":["v2.0.1-rc.14","v2.0.1-rc.13","v2.0.1-rc.12","v2.0.1-rc.11","v2.0.1-rc.10","v2.0.1-rc.9","v2.0.1-rc.8","v2.0.1-rc.7","v2.0.1-rc.6","v2.0.1-rc.5","v2.0.1-rc.4","v2.0.1-rc.3","v2.0.1-rc.2","v2.0.0-rc.1","v2.0.0-beta.5","v2.0.0-beta.4","v2.0.0-beta.3","v2.0.0-beta.2","v2.0.0-beta.1","v2.0.0-beta.0","v1.15.3","v1.12.0","v1.11.1","v1.11.0","v1.10.2","v1.10.1","v1.10.0","v1.9.0","v1.8.2","v1.8.1","v1.8.0","v1.8.0-rc.3","v1.8.0-rc.2","v1.8.0-rc.1","v1.8.0-rc.0","v1.7.1","v1.7.0","v1.6.6","v1.6.5","v1.6.4","v1.6.3","v1.6.2","v1.6.1","v1.6.0","v1.5.0","v1.4.0","v1.3.0","v1.2.1","v1.2.0","v1.1.0","v1.0.2","v1.0.1","v1.0.0","v0.8.6","v0.8.5","v0.8.4","v0.8.3","v0.8.2","v0.8.1","v0.8.0","v0.7.21","v0.7.20","v0.7.19","v0.7.18","v0.7.17","v0.7.16","v0.7.15","v0.7.14","v0.7.13","v0.7.12","v0.7.11","v0.7.10","v0.7.9","v0.7.8","v0.7.7","v0.7.6","v0.7.5","v0.7.4","v0.7.3","v0.7.2","v0.7.1","v0.7.0","v0.6.0","v0.5.7","v0.5.6","v0.5.5","v0.5.4","v0.5.3","v0.5.2","v0.5.1","v0.5.0","v0.4.2","v0.4.1","v0.4.0","v0.3.9","v0.3.8","v0.3.7","v0.3.6","v0.3.5","v0.3.4","v0.3.3","v0.3.2","v0.3.1","v0.3.0","v0.2.12","v0.2.11","v0.2.10","v0.2.9","v0.2.8","v0.2.7","v0.2.6","v0.2.5","v0.2.4","v0.2.3","v0.2.2","v0.2.1","v0.2.0","v0.0.15","v0.0.14","v0.0.13","v0.0.12","v0.0.11","v0.0.10","v0.0.9","v0.0.8","v0.0.7","v0.0.6","v0.0.5","v0.0.4","v0.0.3","v0.0.2","v0.0.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-33131.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"}]}