Resource Exhaustion Affecting puma package, versions <4.3.8-1


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

EPSS
1.6% (73rd percentile)

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  • Snyk IDSNYK-DEBIANUNSTABLE-PUMA-1292169
  • published13 May 2021
  • disclosed11 May 2021

Introduced: 11 May 2021

CVE-2021-29509  (opens in a new tab)
CWE-400  (opens in a new tab)

How to fix?

Upgrade Debian:unstable puma to version 4.3.8-1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream puma package and not the puma package as distributed by Debian. See How to fix? for Debian:unstable relevant fixed versions and status.

Puma is a concurrent HTTP 1.1 server for Ruby/Rack applications. 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. This problem has been fixed in puma 4.3.8 and 5.3.1. 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 and a git patch is available for those using unsupported versions of Puma.

CVSS Base Scores

version 3.1