Status: KEV | Advisory ID: CVE-2026-48710
| CVE | CVE-2026-48710 |
| CVSS | CVSS 6.5 (Medium). |
| Affected products | see table below |
| Exploitation status | Listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, indicating confirmed active exploitation. |
| KEV listing | Added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2026-09-02. |
| Exploitation prediction (EPSS) | 36% probability of exploitation in the next 30 days (98% percentile) -- FIRST.org's EPSS model. |
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.
| Source | Reference |
|---|---|
| NVD | https://nvd.nist.gov/vuln/detail/CVE-2026-48710 |
| Vendor advisory | https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr |