Language: Go
Label: safe
CWE: CWE-287 \u2014 Improper Authentication
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.

Code:
func (m mockAuth) AuthPlain(username, _ string) error {
	ok := m.db[username]
	if !ok {
		return errors.New("invalid creds")
	}
	return nil
}