Vulnerabilities > CVE-2021-21291 - Open Redirect vulnerability in Oauth2 Proxy Project Oauth2 Proxy
Summary
OAuth2 Proxy is an open-source reverse proxy and static file server that provides authentication using Providers (Google, GitHub, and others) to validate accounts by email, domain or group. In OAuth2 Proxy before version 7.0.0, for users that use the whitelist domain feature, a domain that ended in a similar way to the intended domain could have been allowed as a redirect. For example, if a whitelist domain was configured for ".example.com", the intention is that subdomains of example.com are allowed. Instead, "example.com" and "badexample.com" could also match. This is fixed in version 7.0.0 onwards. As a workaround, one can disable the whitelist domain feature and run separate OAuth2 Proxy instances for each subdomain.
Vulnerable Configurations
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Fake the Source of Data An adversary provides data under a falsified identity. The purpose of using the falsified identity may be to prevent traceability of the provided data or it might be an attempt by the adversary to assume the rights granted to another identity. One of the simplest forms of this attack would be the creation of an email message with a modified "From" field in order to appear that the message was sent from someone other than the actual sender. Results of the attack vary depending on the details of the attack, but common results include privilege escalation, obfuscation of other attacks, and data corruption/manipulation.
References
- https://pkg.go.dev/github.com/oauth2-proxy/oauth2-proxy/v7
- https://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-4mf2-f3wh-gvf2
- https://github.com/oauth2-proxy/oauth2-proxy/releases/tag/v7.0.0
- https://github.com/oauth2-proxy/oauth2-proxy/commit/780ae4f3c99b579cb2ea9845121caebb6192f725