CVE-2020-15234: Redirect URL matching ignores character casing

Vulnerability summary

CVE-2020-15234 is a medium (CVSS 6.1) Improper Input Validation vulnerability in ory fosite. EPSS estimates a 0.84% chance of exploitation in the next 30 days, higher than 57.9% of scored vulnerabilities.

Timeline

1. 02-10-2020
   PublishedVulnerability first disclosed.
2. 04-08-2024
   Last modifiedVulnerability information updated.

Description

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.

• CWE-20Improper Input ValidationThe product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
• CWE-601URL Redirection to Untrusted SiteThe web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.
• CWE-178Improper Handling of Case SensitivityThe product does not properly account for differences in case sensitivity when accessing or determining the properties of a resource, leading to inconsistent results.