CVE-2026-48817 Starlette: Arbitrary HTTP method dispatched to `HTTPEndpoint` attributes via `getattr`

Medium 5.3 Published 17 Jun 2026 Updated 18 Jun 2026

Attackers can invoke internal endpoint methods as HTTP handlers by using non-standard verbs, bypassing authorization checks in Starlette applications.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2026-48817?

CVE-2026-48817 is a medium-severity missing authorization vulnerability in Kludex starlette, published on 17 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Starlette is a lightweight ASGI framework/toolkit. In versions 1.0.1 and below, when dispatching a request, HTTPEndpoint selects the handler by lowercasing the HTTP method and looking it up as an attribute with getattr, without restricting the lookup to a known set of HTTP verbs. When an HTTPEndpoint subclass is registered through Route(...) without an explicit methods= argument, the route does not constrain the method and every method reaches the endpoint. If a non-standard HTTP method whose lowercased name matches an attribute on the endpoint subclass reaches the endpoint, that attribute is invoked as if it were a request handler. An attacker can use this to reach methods that were never meant to be HTTP handlers, such as internal helpers, without the authorization checks applied by the intended public handler. An application (including Starlette-based frameworks like FastAPI) is affected if it registers an HTTPEndpoint subclass via Route(...) without explicitly setting methods=, and that subclass includes extra methods named like non-standard HTTP verbs that take one request argument and return a response. This issue has been fixed in version 1.1.0.

Weakness: CWE-470

Which versions are affected by CVE-2026-48817?

3 open source packages ship an affected version, including starlette. It affects 1 product.

Package	Affected	Fixed in
`starlette` PyPI	All versions	`1.1.0`
`starlette` PyPI	All versions	`1.1.0`
`starlette` PyPI	All versions	`1.1.0`

Products include Encode Starlette.

How do I fix CVE-2026-48817?

Upgrade starlette to 1.1.0 or later.

Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.

Is CVE-2026-48817 being exploited?

There is no known exploitation of CVE-2026-48817 in the wild and no public exploit code.

Sources

Also known as CLEANSTART-2026-OL54879, CLEANSTART-2026-RX49368, DEBIAN-CVE-2026-48817, ECHO-0b16-11b5-0d47, GHSA-x746-7m8f-x49c, MINI-2c76-v662-vqgx and 18 more.