CVE-2021-295097.5HighCWE-400

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

puma

Vendor fix available · Affected: puma · Exploitation: possible (1 to 10%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

1.6%probability of exploitation in the next 30 days

76th percentile

050100

Higher than 76% of scored CVEs

7.5HighCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

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.

Affected products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

puma · puma< 4.3.8; >= 5.0.0, < 5.3.1

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas

Exploitation: Possible (1 to 10%). EPSS between 1% and 10%.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Uncontrolled Resource Consumption · Denial of Service
Vendor: puma
Published: May 2021
Band: Possible (1 to 10%), May 2021

CoverageNo articles yet

No CyberSIXT article names CVE-2021-29509 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.