CSRF Protection

Сross-Site Request Forgery (CSRF) protection in TeamCity implies a number of requirements on HTTP requests.

Since version 2020.1, TeamCity uses only CSRF tokens as a protection measure. In previous versions of TeamCity, Origin/Referer headers were also used.

To obtain a security token, send the GET https://your-server/authenticationTest.html?csrf request.
To pass the token, use the X-TC-CSRF-Token HTTP request header or the tc-csrf-token HTTP parameter.

CSRF checks for HTTP request

When considering HTTP request safety from the TeamCity perspective, the following checks are sequentially made:

If an HTTP request is a non-modifying one (such as GET), it is considered safe.
If an HTTP request has a secure CSRF token either in the parameter or in the HTTP header and this token matches the one stored in user session, it is considered safe.

Implications for non-browser HTTP clients

For non-browser API access, we recommend using token-based authentication.

Implications for CORS clients

To use CORS request, configure the CORS support as described here. This configuration will be enough for GET requests.
If you need to send POST/PUT/DELETE requests via CORS, you should obtain a CSRF token using the authenticationTest.html?csrf call, and then provide this token with your modifying HTTP requests.

Troubleshooting

If you face problems regarding CSRF protection in TeamCity (for example, you get the "Responding with 403 status code due to failed CSRF check" response from the server), you can try these steps:

Enforce verification of Origin/Referer headers for CORS operations by setting the teamcity.csrf.paranoid=false internal property, similarly to how it worked in TeamCity versions prior to 2020.1 (read our Upgrade Notes) for more details).
Temporary disable CSRF protection at all by setting the teamcity.csrf.origin.check.enabled=logOnly internal property.
Information about failed CSRF attempts is logged into TeamCity/logs/teamcity-auth.log files. For more detailed diagnostics of the requests, enable the debug-auth logging preset.

In case none of the listed steps help to resolve your problem, please contact our support and provide your teamcity-auth.log logs with the enabled teamcity-auth logging preset.

Last modified: 10 December 2021