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Common CSRF pitfalls

Because Ory Hydra isn't just an API, but instead talks to your users' browsers directly, several security measures have been implemented in Ory Kratos. One of them is protection against CSRF:

CSRF is an attack that tricks the victim into submitting a malicious request. It inherits the identity and privileges of the victim to perform an undesired function on the victim’s behalf. For most sites, browser requests automatically include any credentials associated with the site, such as the user’s session cookie, IP address, Windows domain credentials, and so forth. Therefore, if the user is authenticated to the site, the site will have no way to distinguish between the forged request sent by the victim and a legitimate request sent by the victim.

Source

Common pitfalls​

Sometimes, cookies and CSRF just wont work - all requests end up with a 401 Unauthorized or 400 Bad Request. Here are some common causes and easy fixes if that happens to you!

Before starting to debug cookie and CSRF issues, make sure to check out the Chrome Developer Tools (or any comparable technology) Cookies tabs in the Application tab

Google Chrome Developer Tools - Application Tab - Cookies

as well as the network tab - look for Cookie and Set-Cookie HTTP Headers:

Google Chrome Developer Tools - Network Tab - Cookies

Same-site in Chrome​

Google Chrome changed the behavior of SameSite=None so that it isn't possible to use this SameSite mode without the HTTP Cookie secure flag.

If you run a version of Ory Hydra 1.6 and below and experience this issue:

  • Make sure to not use the --dangerous-force-http flag
  • Set configuration value serve.cookies.same_site_mode or environment variable SERVE_COOKIES_SAME_SITE_MODE to Lax - this happens automatically for Ory Hydra v1.7.0 when running in HTTP mode.

Chrome rejects cookies without the secure flag if a cookie with the same name for the same scope (domain, path) is set that has the secure flag. Ory Hydra 1.7.0+ uses different names for cookies with and without secure flag. For versions prior to that, you need to delete the cookies for the domain in order to get them working again.

Ory Hydra Running Over HTTP Without dev-mode Enabled​

You are running Ory Hydra via HTTP but are missing the --dangerous-force-http CLI flag:

hydra serve all -c path/to/config.yml --dangerous-force-http

Mixing up 127.0.0.1 and localhost​

Use either 127.0.0.1 or localhost - so either IPs or hostnames - throughout your flow because cookies from an IP aren't available to the hostname and vice-versa.

Reverse proxy or load balancers​

You are running Ory Hydra behind a reverse proxy that strips the Cookie header. If the reverse proxy supports path rewrites that might also cause issues!

Running flows in separate browsers or browser windows​

You are running the OAuth2 flow in separate browsers, or in a browser with incognito mode. The Brave browser is also known for notoriously discarding cookies when used in "No-Tracking" mode.

Running Multiple OAuth2 Flows Simultaneously​

You are trying to do two OAuth2 flows at the same time in the same Browser.

You have changed the Cookie SameSite behavior. If this is the default value (you didn't change it), this shouldn't be an issue.

Using AJAX to call /oauth2/auth​

You can't call /oauth2/auth using an AJAX request. It isn't allowed and not possible with OAuth2. This endpoint can only be accessed using a normal browser request by clicking a link or redirecting the end-user's browser to that endpoint.