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🚨 [security] Update puma: 4.3.5 → 4.3.12 (patch) #382

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🚨 [security] Update puma: 4.3.5 → 4.3.12 (patch) #382

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🚨 Your current dependencies have known security vulnerabilities 🚨

This dependency update fixes known security vulnerabilities. Please see the details below and assess their impact carefully. We recommend to merge and deploy this as soon as possible!

Here is everything you need to know about this update. Please take a good look at what changed and the test results before merging this pull request.

What changed?

✳️ puma (4.3.5 → 4.3.12) · Repo · Changelog

Security Advisories 🚨

🚨 HTTP Request Smuggling in puma

Impact

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.

Patches

The vulnerability has been fixed in 5.6.4 and 4.3.12.

Workarounds

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)

References

HTTP Request Smuggling

🚨 Information Exposure with Puma when used with Rails

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 7.0.2.2, 6.1.4.6, 6.0.4.6, and 5.2.6.2.

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

🚨 Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling') in puma

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

🚨 Keepalive Connections Causing Denial Of Service in puma

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.

Release Notes

4.3.12

Security

4.3.11

4.3.10

Re-allows UTF-8 in HTTP header values

4.3.9

GHSA-48w2-rm65-62xx

4.3.8

  • Security
    • Close keepalive connections after the maximum number of fast inlined requests (#2625)

4.3.7 (from changelog)

  • Bugfixes
    • Backport set CONTENT_LENGTH for chunked requests (Originally: #2287, backport: #2496)

4.3.6

v4.3.5...4.3.6

A quick fix for a build error on Mac OS and a JSON require fix for those using phased restart.

  • Explicitly include ctype.h to fix compilation warning and build error on macOS with Xcode 12 (#2304)
  • Don't require json at boot (#2269)

Does any of this look wrong? Please let us know.

Commits

See the full diff on Github. The new version differs by 19 commits:

↗️ nio4r (indirect, 2.5.2 → 2.5.8) · Repo · Changelog

Release Notes

2.5.4 (from changelog)

2.5.3 (from changelog)

Does any of this look wrong? Please let us know.

Commits

See the full diff on Github. The new version differs by 75 commits:

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