Implicit clients can be subject to an attack that utilizes the fact that user agents re-attach fragments to the destination URL of a redirect if the location header does not contain a fragment. This allows circumvention even of very narrow redirect URI patterns, but not strict URL matching.
OAuth 2.0 Security Best Current Practice (SecBCP, section 4.1.2)
This threat is considered fully mitigated if all the test cases from one of the following test sets succeed.
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