How severe is CVE-2024-21647?

CVE-2024-21647 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2024-21647 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (57th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2024-21647?

CVE-2024-21647 affects Puma. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2024-21647?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2024-21647 have an EU (EUVD) identifier?

Yes. CVE-2024-21647 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-0323.

When was CVE-2024-21647 published?

CVE-2024-21647 was published on 2024-01-08 and last updated on 2026-06-17.

CVE-2024-21647

CVE-2024-21647 is a medium-severity vulnerability in Puma with a CVSS 3.x base score of 5.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-444.

Key facts

Severity: Medium (CVSS 3.x base score 5.9)
EPSS exploit prediction: 1% (57th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2024-0323
Weakness: CWE-444
Affected product: Puma
Published: 2024-01-08
Last modified: 2026-06-17

Description

Puma is a web server for Ruby/Rack applications built for parallelism. Prior to version 6.4.2, puma exhibited incorrect behavior when parsing chunked transfer encoding bodies in a way that allowed HTTP request smuggling. Fixed versions limits the size of chunk extensions. Without this limit, an attacker could cause unbounded resource (CPU, network bandwidth) consumption. This vulnerability has been fixed in versions 6.4.2 and 5.6.8.

Frequently asked questions

What is CVE-2024-21647?: Puma is a web server for Ruby/Rack applications built for parallelism. Prior to version 6.4.2, puma exhibited incorrect behavior when parsing chunked transfer encoding bodies in a way that allowed HTTP request smuggling. Fixed versions limits the size of chunk extensions. Without this limit, an attacker could cause unbounded resource (CPU, network bandwidth) consumption. This vulnerability has been fixed in versions 6.4.2 and 5.6.8.
How severe is CVE-2024-21647?: CVE-2024-21647 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2024-21647 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (57th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2024-21647?: CVE-2024-21647 affects Puma. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2024-21647?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2024-21647 have an EU (EUVD) identifier?: Yes. CVE-2024-21647 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-0323.
When was CVE-2024-21647 published?: CVE-2024-21647 was published on 2024-01-08 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:puma:puma:*:*:*:*:*:ruby:*:*

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