CVE-2020-15234: Redirect URL matching ignores character casing
ORY Fosite is a security first OAuth2 & OpenID Connect framework for Go. In Fosite before version 0.34.1, the OAuth 2.0 Client's registered redirect URLs and the redirect URL provided at the OAuth2 Authorization Endpoint where compared using strings.ToLower while they should have been compared with a simple string match. This allows an attacker to register a client with allowed redirect URL https://example.com/callback. Then perform an OAuth2 flow and requesting redirect URL https://example.com/CALLBACK. Instead of an error (invalid redirect URL), the browser is redirected to https://example.com/CALLBACK with a potentially successful OAuth2 response, depending on the state of the overall OAuth2 flow (the user might still deny the request for example). This vulnerability has been patched in ORY Fosite v0.34.1.
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Frequently Asked Questions
What is the severity of CVE-2020-15234?
CVE-2020-15234 has been assessed with a medium severity rating due to the potential for security bypass in OAuth 2.0 client redirect URLs.
How do I fix CVE-2020-15234?
To resolve CVE-2020-15234, upgrade your Fosite implementation to version 0.34.1 or later, which addresses the redirect URL comparison issue.
What vulnerabilities are associated with CVE-2020-15234?
CVE-2020-15234 specifically affects the comparison mechanism of redirect URLs in the Fosite framework, potentially allowing attackers to bypass security checks.
Who is affected by CVE-2020-15234?
Users of Fosite versions prior to 0.34.1 are at risk and should immediately consider updating to the patched version to mitigate this vulnerability.
What type of application does CVE-2020-15234 impact?
CVE-2020-15234 impacts applications utilizing the Fosite framework for implementing OAuth 2.0 and OpenID Connect protocols.