BCP_4_1_2

Redirect URI Validation Attacks on Implicit Grant

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 (draft 25) (SecBCP, section 4.1.2)

Mitigations

This threat is considered fully mitigated if all the test cases from one of the following test sets succeed.

• Set #1
• AuthEndpoint.RedirectUriFullyMatchedTest
• Set #2
• AuthEndpoint.RedirectUriPathMatchedTest
• AuthEndpoint.RedirectUriConfusionTest
• AuthEndpoint.FragmentFixTest

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