CVE-2026-48710 (GCVE-0-2026-48710)
Vulnerability from cvelistv5
Published
2026-05-26 21:54
Modified
2026-05-27 14:26
CWE
  • CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Summary
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.
Impacted products
Vendor Product Version
Kludex starlette Version: < 1.0.1
Create a notification for this product.
Show details on NVD website


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                "id": "CVE-2026-48710",
                "options": [
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                "timestamp": "2026-05-27T14:22:19.241769Z",
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          "value": "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 \u00a73.2 / RFC 3986 \u00a73.2.2 when constructing `request.url` and falls back to `scope[\"server\"]` for malformed values."
        }
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            "baseScore": 6.5,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "LOW",
            "privilegesRequired": "NONE",
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            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N",
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          "name": "https://ostif.org/disclosing-the-badhost-vulnerability-in-starlette",
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      "source": {
        "advisory": "GHSA-86qp-5c8j-p5mr",
        "discovery": "UNKNOWN"
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      "title": "Starlette has missing Host header validation that poisons request.url.path, bypassing path-based security checks"
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    "dateReserved": "2026-05-22T18:47:27.755Z",
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