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CVE-2021-29509

CVE information

Published

1 year ago

Last Modified

4 weeks ago

CVSSv2.0 Severity

Medium

CVSSv3.1 Severity

High

Impact Analysis

Description

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..

CVSSv2.0 Score

Severity
Medium
Base Score
5/10
Exploit Score
10/10
Access Vector
Network
Access Complexity
Low
Authentication Required
None
Impact Score
2.9/10
Confidentiality Impact
None
Availability Impact
Partial
Integrity Impact
None

CVSSv3.1 Score

Severity
High
Base Score
7.5/10
Exploit Score
3.9/10
Access Vector
Network
Access Complexity
Low
Privileges Required
None
Impact Score
3.6/10
Confidentiality Impact
None
Availability Impact
High
Integrity Impact
None
Scope
Unchanged
User Interaction
None

Products Affected

CPE Affected Vulnerable Excluding Edit
cpe:2.3:a:puma:puma:*:*:*:*:*:ruby:*:*
  Yes
5.0.0 5.3.1
cpe:2.3:a:puma:puma:*:*:*:*:*:ruby:*:*
  Yes
- 4.3.8
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
  Yes
- -