{"id":"CVE-2026-48710","summary":"Starlette has missing Host header validation that poisons request.url.path, bypassing path-based security checks","details":"Starlette is a lightweight ASGI framework/toolkit. Prior to version 1.0.1, the HTTP `Host` request header was not validated before being used to reconstruct `request.url`. Because the routing algorithm relies on the raw HTTP path while `request.url` is rebuilt from the `Host` header, a malformed header could make `request.url.path` differ from the path that was actually requested. Middleware and endpoints that apply security restrictions based on `request.url` (rather than the raw `scope` path) could therefore be bypassed. Users should upgrade to a version greater than or equal to version 1.0.1, which validates the `Host` header against the grammar of RFC 9112 §3.2 / RFC 3986 §3.2.2 when constructing `request.url` and falls back to `scope[\"server\"]` for malformed values.","aliases":["GHSA-86qp-5c8j-p5mr","PYSEC-2026-161","X41-2026-002"],"modified":"2026-06-25T04:04:14.695776907Z","published":"2026-05-26T21:54:54.393Z","related":["CGA-vxhx-m86x-8c2h","SUSE-SU-2026:22151-1","openSUSE-SU-2026:11026-1","openSUSE-SU-2026:11044-1","openSUSE-SU-2026:20975-1"],"database_specific":{"cwe_ids":["CWE-444"],"cna_assigner":"GitHub_M","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48710.json"},"references":[{"type":"WEB","url":"https://badhost.org"},{"type":"WEB","url":"https://ostif.org/disclosing-the-badhost-vulnerability-in-starlette"},{"type":"WEB","url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-48710.json"},{"type":"WEB","url":"https://www.cve.org/CVERecord?id=CVE-2026-48710"},{"type":"WEB","url":"https://www.secwest.net/starlette"},{"type":"ADVISORY","url":"https://access.redhat.com/security/cve/CVE-2026-48710"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48710.json"},{"type":"ADVISORY","url":"https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr"},{"type":"ADVISORY","url":"https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-161.yaml"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-48710"},{"type":"ADVISORY","url":"https://www.x41-dsec.de/lab/advisories/x41-2026-002-starlette"},{"type":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2481742"},{"type":"FIX","url":"https://github.com/Kludex/starlette/commit/764dab0dcfb9033d75442d7a359645c9f94648c6"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/kludex/starlette","events":[{"introduced":"3a16d660490b54daad5711749fa00fd7a0970b4e"},{"fixed":"48f8e331b23ca692f4713ac1f370bff1b5cd034c"},{"fixed":"764dab0dcfb9033d75442d7a359645c9f94648c6"}],"database_specific":{"extracted_events":[{"introduced":"0.8.3"},{"fixed":"1.0.1"}],"cpe":"cpe:2.3:a:encode:starlette:*:*:*:*:*:python:*:*","source":["CPE_RANGE","REFERENCES"]}}],"versions":["1.0.0","1.0.0rc1","0.52.1","0.52.0","0.51.0","0.50.0","0.49.3","0.49.2","0.49.1","0.49.0","0.48.0","0.47.3","0.47.2","0.47.1","0.47.0","0.46.2","0.46.1","0.46.0","0.45.3","0.45.2","0.45.1","0.45.0","0.44.0","0.43.0","0.42.0","0.41.3","0.41.2","0.41.1","0.41.0","0.40.0","0.39.2","0.39.1","0.39.0","0.38.6","0.38.5","0.38.4","0.38.3","0.38.2","0.38.1","0.38.0","0.37.2","0.37.1","0.37.0","0.36.3","0.36.2","0.36.1","0.36.0","0.35.1","0.35.0","0.34.0","0.33.0","0.32.0.post1","0.32.0","0.31.1","0.31.0","0.30.0","0.29.0","0.28.0","0.27.0","0.26.1","0.26.0.post1","0.26.0","0.25.0","0.24.0","0.23.1","0.23.0","0.22.0","0.21.0","0.20.4","0.20.3","0.20.2","0.20.1","0.20.0","0.19.1","0.19.0","0.18.0","0.17.1","0.17.0","0.16.0","0.15.0","0.14.2","0.14.1","0.14.0","0.13.8","0.13.7","0.13.6","0.13.5","0.13.4","0.13.3","0.13.2","0.13.1","0.13.0","0.12.13","0.12.12","0.12.11","0.12.9","0.12.8","0.12.7","0.12.6","0.12.5","0.12.4","0.12.3","0.12.2","0.12.0","0.12.0.b3","0.12.0.b2","0.12.0.b1","0.11.4","0.11.3","0.11.2","0.11.1","0.10.4","0.10.1","0.10.0","0.9.11","0.9.10","0.9.9","0.9.8","0.9.7","0.9.6","0.9.5","0.9.4","0.9.3","0.9.2","0.9.1","0.9.0","0.8.8","0.8.7","0.8.6","0.8.5","0.8.4","0.8.3"],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-48710.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N"}]}