Puma used with Rails may lead to Information Exposure

Impact

Prior to puma version 5.6.2, puma may not always call close on the response body. Rails, prior to version 7.0.2.2, depended on the response body being closed in order for its CurrentAttributes implementation to work correctly.

From Rails:

> Under certain circumstances response bodies will not be closed, for example a bug in a webserver[1] or a bug in a Rack middleware. In the event a response is not notified of a close, ActionDispatch::Executor will not know to reset thread local state for the next request. This can lead to data being leaked to subsequent requests, especially when interacting with ActiveSupport::CurrentAttributes.

The combination of these two behaviors (Puma not closing the body + Rails’ Executor implementation) causes information leakage.

Patches

This problem is fixed in Puma versions 5.6.2 and 4.3.11.

This problem is fixed in Rails versions 7.02.2, 6.1.4.6, 6.0.4.6, and 5.2.6.2.

See:
https://github.com/advisories/GHSA-wh98-p28r-vrc9
for details about the rails vulnerability

Upgrading to a patched Rails or Puma version fixes the vulnerability.

Workarounds

Upgrade to Rails versions 7.02.2, 6.1.4.6, 6.0.4.6, and 5.2.6.2.

The Rails CVE includes a middleware that can be used instead.

References

• Rails CVE: CVE-2022-23633

For more information

If you have any questions or comments about this advisory:

• Open an issue in puma
• See our security policy