CVE-2021-21291: oauth2_proxy_project oauth2_proxy Open Redirect

Vulnerability summary

CVE-2021-21291 is a medium (CVSS 6.1) Open Redirect vulnerability in oauth2_proxy_project oauth2_proxy. EPSS estimates a 1.58% chance of exploitation in the next 30 days, higher than 75.1% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 02-02-2021
   PublishedVulnerability first disclosed.
2. 03-08-2024
   Last modifiedVulnerability information updated.

Description

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.

• CWE-601URL Redirection to Untrusted Site ('Open Redirect')The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.