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CVE-2021-29509— Keepalive Connections Causing Denial Of Service in puma

Quick assessment

Affected
puma puma
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Puma是美国Evan Phoenix个人开发者的一款针对高并发应用的Web服务器。 Puma 存在安全漏洞。该漏洞源于程序中的持久连接会使群集中所有进程中的所有线程饱和。

CVSS 7.5 · High EPSS 1.60% · P73
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I. Basic Information for CVE-2021-29509

Vulnerability Information
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Vulnerability Title
Keepalive Connections Causing Denial Of Service in puma
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
未加控制的资源消耗(资源穷尽)
Source: CVE Program / CVE List V5
Vulnerability Title
Puma 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Puma是美国Evan Phoenix个人开发者的一款针对高并发应用的Web服务器。 Puma 存在安全漏洞。该漏洞源于程序中的持久连接会使群集中所有进程中的所有线程饱和。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
puma puma < 4.3.8 -

II. Public POCs for CVE-2021-29509

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III. Intelligence Information for CVE-2021-29509

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Vendor Advisories for CVE-2021-29509 (2)

Mailing List Discussions for CVE-2021-29509 (1)

Other References for CVE-2021-29509 (3)

IV. Related Vulnerabilities

Same product: puma
Same vendor: puma
Same weakness: CWE-400

V. Comments for CVE-2021-29509

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