CVE-2026-48710

Affected products

Description

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: NVD

References

• [NVD]https://nvd.nist.gov/vuln/detail/CVE-2026-48710
• [Other]https://badhost.org
• [Patch]https://github.com/Kludex/starlette/commit/764dab0dcfb9033d75442d7a359645c9f94648c6
• [Vendor advisory]https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr
• [Other]https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-161.yaml
• [Other]https://ostif.org/disclosing-the-badhost-vulnerability-in-starlette
• [Exploit reference]https://www.secwest.net/starlette
• [Exploit reference]https://www.x41-dsec.de/lab/advisories/x41-2026-002-starlette
• [Other]https://access.redhat.com/security/cve/CVE-2026-48710
• [Other]https://badhost.org
• [Patch]https://github.com/Kludex/starlette/commit/764dab0dcfb9033d75442d7a359645c9f94648c6
• [Vendor advisory]https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr
• [Other]https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-161.yaml
• [Other]https://ostif.org/disclosing-the-badhost-vulnerability-in-starlette
• [Other]https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-48710.json
• [Other]https://www.cve.org/CVERecord?id=CVE-2026-48710
• [Exploit reference]https://www.secwest.net/starlette
• [Exploit reference]https://www.x41-dsec.de/lab/advisories/x41-2026-002-starlette

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