CVE-2026-48710
MediumCVSS 6.5Exploitation Probability (EPSS)
Elevated risk70th percentile - higher than 70% of all known CVEs
Summary
In Starlette prior to version 1.0.1, the HTTP `Host` request header was not validated before being used to reconstruct `request.url`. Since the routing algorithm relies on the raw HTTP path while `request.url` is rebuilt from the `Host` header, a malformed header can make `request.url.path` differ from the actual requested path. This allows bypassing security restrictions in middleware and endpoints that rely on `request.url` instead of the raw `scope` path.
Risk Assessment
The organization is at risk of bypassing access controls and other URL-based security measures, potentially leading to unauthorized access to resources or data disclosure.
Recommendation
Upgrade Starlette to version 1.0.1 or later, which validates the `Host` header against RFC 9112 §3.2 / RFC 3986 §3.2.2 and falls back to `scope["server"]` for malformed values.
Original NVD description (English source)
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.