CVE-2026-48817: Starlette is a lightweight ASGI framework/toolkit. In versions 1.0.1 and below, when dispatching a request, HTTPEndpoint selects the handler by lowerc...

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.

Metrics

CVSS 3.1

5.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS Probability

0.21%

11.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-470

Affected Software

Vendor	Product	Versions
Encode	Starlette	< 1.1.0

References

https://github.com/Kludex/starlette/releases/tag/1.1.0Release Notes
https://github.com/Kludex/starlette/security/advisories/GHSA-x746-7m8f-x49cMitigation, Vendor Advisory

Timeline

Published: Jun 17, 2026
Last Modified: Jun 26, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-48817?

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.

How severe is CVE-2026-48817?

CVE-2026-48817 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.21% probability of exploitation in the next 30 days.

How do I fix CVE-2026-48817?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

How Strix Helps

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