{"id":"CVE-2026-48710","aliases":["GHSA-86qp-5c8j-p5mr","PYSEC-2026-161","X41-2026-002"],"url":"https://o3.security/vulnerability/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.","published":"2026-05-26T21:54:54.393Z","modified":"2026-08-30T03:30:50.263664103Z","cvss":{"score":6.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N"},"epss":{"score":0.01905,"percentile":0.78142,"asOf":"2026-08-24"},"cisaKev":null,"exploitsKnown":1,"affectedPackages":[{"ecosystem":"PyPI","name":"starlette","fixedVersion":"1.0.1"}],"fix":{"url":"https://github.com/Kludex/starlette/commit/764dab0dcfb9033d75442d7a359645c9f94648c6","label":"Kludex/starlette@764dab0"},"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.secwest.net/starlette"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:22992"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:22993"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:23346"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:24866"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:26226"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:30088"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:30089"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:34456"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:34526"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:34532"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:37275"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:43038"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:44696"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:51357"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:60520"},{"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"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-30T03:30:50.263664103Z"}}