CVE-2026-48710

Known Exploited Vulnerability

Kludex Starlette HTTP Request/Response Smuggling Vulnerability

Vendor / product: Kludex / Starlette

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.

Weakness classification

• security-advisories@github.com: CWE-444
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c: CWE-1289

Primary references

• security-advisories@github.com — Mitigation, Third Party Advisory
• security-advisories@github.com — Patch
• security-advisories@github.com — Vendor Advisory
• security-advisories@github.com — Third Party Advisory
• security-advisories@github.com — Mitigation, Third Party Advisory
• security-advisories@github.com — Exploit, Mitigation, Third Party Advisory
• security-advisories@github.com — Exploit, Mitigation, Third Party Advisory
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c — Third Party Advisory
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c — Third Party Advisory
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c — Third Party Advisory
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c — Third Party Advisory
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c — Third Party Advisory