The example code for the digest authentication functionality (http_authentication.rb) in Ruby on Rails before 2.3.3 defines an authenticate_or_request_with_http_digest block that returns nil instead of false when the user does not exist, which allows context-dependent attackers to bypass authentication for applications that are derived from this example by sending an invalid username without a password.
{
"cwe_ids": [
"CWE-287"
],
"github_reviewed": true,
"github_reviewed_at": "2020-06-16T21:56:22Z",
"nvd_published_at": "2009-07-10T15:30:00Z",
"severity": "CRITICAL"
}