Oauth2 Proxy Project: >> Oauth2 Proxy >> 5.1.0 Security Vulnerabilities
OAuth2-Proxy is an open-source tool that can act as either a standalone reverse proxy or a middleware component integrated into existing reverse proxy or load balancer setups. In versions 7.10.0 and below, oauth2-proxy deployments are vulnerable when using the skip_auth_routes configuration option with regex patterns. Attackers can bypass authentication by crafting URLs with query parameters that satisfy configured regex patterns, allowing unauthorized access to protected resources. The issue stems from skip_auth_routes matching against the full request URI. Deployments using skip_auth_routes with regex patterns containing wildcards or broad matching patterns are most at risk. This issue is fixed in version 7.11.0. Workarounds include: auditing all skip_auth_routes configurations for overly permissive patterns, replacing wildcard patterns with exact path matches where possible, ensuring regex patterns are properly anchored (starting with ^ and ending with $), or implementing custom validation that strips query parameters before regex matching.
CVSS Score
9.1
EPSS Score
0.005
Published
2025-07-30
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.
CVSS Score
4.7
EPSS Score
0.002
Published
2021-02-02
In OAuth2 Proxy before 5.1.1, there is an open redirect vulnerability. Users can provide a redirect address for the proxy to send the authenticated user to at the end of the authentication flow. This is expected to be the original URL that the user was trying to access. This redirect URL is checked within the proxy and validated before redirecting the user to prevent malicious actors providing redirects to potentially harmful sites. However, by crafting a redirect URL with HTML encoded whitespace characters the validation could be bypassed and allow a redirect to any URL provided. This has been patched in 5.1.1.
CVSS Score
7.1
EPSS Score
0.002
Published
2020-05-07