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Vulnerabilities

Vulnerability · CVE-2026-48817

Arbitrary HTTP method dispatched to attributes via

Published May 23, 2026 · catalog updated May 28, 2026 · Arbitrary HTTP method dispatched

Last checked Nov 2, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-48817. EPSS is 0.21%. Act only if a listed version of Arbitrary HTTP method dispatched is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Arbitrary HTTP method dispatched).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium5.3
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.21%
Remediation
Version ranges on file
Affected products
pip starlette

### Summary When dispatching a request, selects the handler by lowercasing the HTTP method and looking it up as an attribute with , without restricting the lookup to a known set of HTTP verbs. When an subclass is registered through without an explicit 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. ### Details uses the client-supplied method name to resolve an instance attribute, without validating it against the set of HTTP verbs the endpoint supports. A method such as therefore resolves an attribute like and invokes it. Non-standard methods are valid [RFC 9110](https://www.rfc-editor.org/rfc/rfc9110#name-method) token methods, so an endpoint must not treat the method name as a trusted attribute selector. ### Impact An application is affected when all of the following hold: * It defines an subclass and registers it via without an explicit argument. * The subclass defines additional methods whose names match a non-standard HTTP-method token shape and that accept a single argument and return a response. This also affects frameworks built on Starlette, like FastAPI. ### Mitigation Register subclasses with an explicit argument on the , listing only the HTTP verbs the endpoint supports. The route then rejects any other method with before it reaches the endpoint, so non-standard methods cannot resolve an attribute.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • pip starlette< 1.1.0

How to fix CVE-2026-48817

  • Upgrade

    CVE-2026-48817 lists a fix boundary at 1.1.0. Compare the installed build with that boundary before you change production.

  • Version check

    Affected < 1.1.0

  • Advisory

    Open the inventory_github record and follow its fix.

  • Official advisories

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-48817. EPSS is 0.21%. Act only if a listed version of Arbitrary HTTP method dispatched is installed.

Which versions are affected?

Compare what you have installed with < 1.1.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-470. EPSS 0.21%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Starlette security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. May 23, 2026 · Maintainer security tabs

    Detected

    ### Summary When dispatching a request, selects the handler by lowercasing the HTTP method and looking it up as an attribute with , without restricting the lookup to a known set of HTTP verbs. When an subclass is registered through without an explicit argument, the route does not constrain the method and every method reaches the endpoint. If a non-standard HTTP method whose lowercased name matches

  2. May 28, 2026 · Maintainer security tabs

    Updated

    ### Summary When dispatching a request, selects the handler by lowercasing the HTTP method and looking it up as an attribute with , without restricting the lookup to a known set of HTTP verbs. When an subclass is registered through without an explicit argument, the route does not constrain the method and every method reaches the endpoint. If a non-standard HTTP method whose lowercased name matches

Sources

  • Maintainer security tabsVendor advisoryGHSA-x746-7m8f-x49c

    ### Summary When dispatching a request, selects the handler by lowercasing the HTTP method and looking it up as an attribute with , without restricting the lookup to a known set of HTTP verbs. When an subclass is registered through without an explicit argument, the route does not constrain the method and every method reaches the endpoint. If a non-standard HTTP method whose lowercased name matches

    github.com

Freshness

Last verified in this catalog Nov 2, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • Maintainer security tabsNov 2, 2026