Update dependency puma to v4 [SECURITY]

[renovate]

This PR contains the following updates:

Package	Update	Change
puma	major	'~> 3.7' -> '~> 4.0'

GitHub Vulnerability Alerts

CVE-2021-29509

This vulnerability is related to CVE-2019-16770.

Impact

The fix for CVE-2019-16770 was incomplete. The original fix only protected existing connections that had already been accepted from having their requests starved by greedy persistent-connections saturating all threads in the same process. However, new connections may still be starved by greedy persistent-connections saturating all threads in all processes in the cluster.

A puma server which received more concurrent keep-alive connections than the server had threads in its threadpool would service only a subset of connections, denying service to the unserved connections.

Patches

This problem has been fixed in puma 4.3.8 and 5.3.1.

Workarounds

Setting queue_requests false also fixes the issue. This is not advised when using puma without a reverse proxy, such as nginx or apache, because you will open yourself to slow client attacks (e.g. slowloris).

The fix is very small. A git patch is available here for those using unsupported versions of Puma.

For more information

If you have any questions or comments about this advisory:

• Open an issue in Puma.
• To report problems with this fix or to report another vulnerability, see our security policy.

Acknowledgements

Thank you to @​MSP-Greg, @​wjordan and @​evanphx for their review on this issue.

Thank you to @​ioquatix for providing a modified fork of wrk which made debugging this issue much easier.

CVE-2021-41136

Impact

Prior to puma version 5.5.0, using puma with a proxy which forwards LF characters as line endings could allow HTTP request smuggling. A client could smuggle a request through a proxy, causing the proxy to send a response back to another unknown client.

This behavior (forwarding LF characters as line endings) is very uncommon amongst proxy servers, so we have graded the impact here as "low". Puma is only aware of a single proxy server which has this behavior.

If the proxy uses persistent connections and the client adds another request in via HTTP pipelining, the proxy may mistake it as the first request's body. Puma, however, would see it as two requests, and when processing the second request, send back a response that the proxy does not expect. If the proxy has reused the persistent connection to Puma to send another request for a different client, the second response from the first client will be sent to the second client.

Patches

This vulnerability was patched in Puma 5.5.1 and 4.3.9.

Workarounds

This vulnerability only affects Puma installations without any proxy in front.

Use a proxy which does not forward LF characters as line endings.

Proxies which do not forward LF characters as line endings:

• Nginx
• Apache (>2.4.25)
• Haproxy
• Caddy
• Traefik

Possible Breakage

If you are dealing with legacy clients that want to send LF as a line ending in an HTTP header, this will cause those clients to receive a 400 error.

References

• HTTP Request Smuggling

For more information

If you have any questions or comments about this advisory:

• Open an issue in Puma
• See our security policy

CVE-2022-23634

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:
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

CVE-2022-24790

When using Puma behind a proxy that does not properly validate that the incoming HTTP request matches the RFC7230 standard, Puma and the frontend proxy may disagree on where a request starts and ends. This would allow requests to be smuggled via the front-end proxy to Puma.

The following vulnerabilities are addressed by this advisory:

• Lenient parsing of Transfer-Encoding headers, when unsupported encodings should be rejected and the final encoding must be chunked.
• Lenient parsing of malformed Content-Length headers and chunk sizes, when only digits and hex digits should be allowed.
• Lenient parsing of duplicate Content-Length headers, when they should be rejected.
• Lenient parsing of the ending of chunked segments, when they should end with \r\n.

The vulnerability has been fixed in 5.6.4 and 4.3.12. When deploying a proxy in front of Puma, turning on any and all functionality to make sure that the request matches the RFC7230 standard.

These proxy servers are known to have "good" behavior re: this standard and upgrading Puma may not be necessary. Users are encouraged to validate for themselves.

• Nginx (latest)
• Apache (latest)
• Haproxy 2.5+
• Caddy (latest)
• Traefik (latest)

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