Lemonldap::NG::Portal vulnerabilities

A vulnerability in Lemonldap::NG::Portal (Perl) allows a PKCE bypass for public Relying Parties in "PKCE or secret" mode because checkEndPointAuthenticationCredentials does not verify the client secret. With oidcRPMetaDataOptionsRequirePKCE set to 2, the authorization endpoint issues a code even without a code_challenge, and token() admits the exchange if a challenge was stored or an authentication method was returned. An attacker can exchange an intercepted authorization code for the user's access, ID, and refresh tokens.

A vulnerability in Lemonldap::NG::Portal (Perl) allows unauthenticated OAuth2 token introspection because checkEndPointAuthenticationCredentials does not verify the client secret of a public Relying Party. The function skips the secret comparison for a public Relying Party and returns the authentication method deduced from the request, so a request with a public client_id and an arbitrary or empty secret passes the endpoint's authentication check. An attacker can confirm the token is active and read its metadata, including scope, audience, expiry, and sub.

Lemonldap::NG::Portal versions from 2.0.0 before 2.16.9, from 2.17.0 before 2.21.5, from 2.22.0 before 2.23.3 for Perl allow authentication bypass via an OAuth2 state parameter stored as an SSO session in the GitHub and LinkedIn backends. An attacker can replay the session identifier as a session cookie and obtain a valid SSO session without authenticating.