CVE-2026-48710
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.
- CVSS 3.1
- 6.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N - EPSS
- 70% chance of exploitation in the next 30 days; higher than 99% of CVEs (scores of 2026-10-25)
- CISA KEV
- listed 2026-09-02, due 2026-09-16
- CWEs
- CWE-444, CWE-1289
- Published
- Modified
- Record from
- the NVD, synced
Affected
- encode:starlette
- redhat:ai_inference_server
- redhat:ansible_automation_platform
- redhat:enterprise_linux_ai
- redhat:migration_toolkit_for_applications
- redhat:openshift_ai
- redhat:openshift_lightspeed
- redhat:satellite
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-86qp-5c8j-p5mr | PyPI | starlette | <1.0.1 | 1.0.1 |
| PYSEC-2026-161 | PyPI | starlette | <1.0.1 | 1.0.1 |
References
- https://badhost.org
- https://github.com/Kludex/starlette/commit/764dab0dcfb9033d75442d7a359645c9f94648c6
- https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr
- https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-161.yaml
- https://ostif.org/disclosing-the-badhost-vulnerability-in-starlette