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CVE-2026-48710

Starlette has missing Host header validation that poisons request.url.path, bypassing path-based security checks

CVSS 6.5 medium · Kludex starlette · published 2026-05-26

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.

NVD · CVE.org

Coverage 1 source

  1. 2026-09-02 CISA Cybersecurity Advisories high CISA Adds Seven Known Exploited Vulnerabilities to Catalog

    CISA added 7 new vulnerabilities to its Known Exploited Vulnerabilities Catalog.

Mentioned with

CVE-2026-49869 CVE-2026-59822 CVE-2026-82329 CVE-2026-9586

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