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TI-2020-04303 Aliases CVE-2020-5247GHSA-84j7-475p-hp8v

HTTP Response Splitting in Puma

Priority LOW 38CWE-113Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
None · High · None
Fix status
Partial Red Hat: 4 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA, GitHub and Red Hat.

Summary

In Puma (RubyGem) before 4.3.2 and before 3.12.3, if an application using Puma allows untrusted input in a response header, an attacker can use newline characters (i.e. `CR`, `LF` or`/r`, `/n`) to end the header and inject malicious content, such as additional headers or an entirely new response body. This vulnerability is known as HTTP Response Splitting. While not an attack in itself, response splitting is a vector for several other attacks, such as cross-site scripting (XSS). This is related to CVE-2019-16254, which fixed this vulnerability for the WEBrick Ruby web server. This has been fixed in versions 4.3.2 and 3.12.3 by checking all headers for line endings and rejecting headers with those characters.

Why it matters now

EPSS 0.02549 85th percentileScored 2026-11-07
Fix Partial Puma (puma): 3.12.3, 4.3.2puma (RubyGems): 3.12.4, 4.3.3Red Hat: 4 without a fix

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
pumaPumabefore 3.12.3; 4.0.0 to before 4.3.23.12.3, 4.3.2Patch availableCNA
—puma (RubyGems)before 3.12.43.12.4Patch availableGHSA-84j7-475p-hp8v
—puma (RubyGems)4.0.0 to before 4.3.34.3.3Patch availableGHSA-84j7-475p-hp8v
  • Puma Vendorpuma Affected before 3.12.3; 4.0.0 to before 4.3.2 Fixed in 3.12.3, 4.3.2 Patch available CNA
  • puma (RubyGems) Vendor— Affected before 3.12.4 Fixed in 3.12.4 Patch available GHSA-84j7-475p-hp8v
  • puma (RubyGems) Vendor— Affected 4.0.0 to before 4.3.3 Fixed in 4.3.3 Patch available GHSA-84j7-475p-hp8v

CPE configurations NVD · 7

CPEVersionsRoleVendor
cpe:2.3:a:puma:puma:*:*:*:*:*:ruby:*:*up to 3.12.3; 4.0.0 – 4.3.2Vulnerablepuma
cpe:2.3:a:ruby-lang:ruby:*:*:*:*:*:*:*:*up to 2.3.0; 2.4.0 – 2.4.7; 2.5.0 – 2.5.6; 2.6.0 – 2.6.4Vulnerableruby
cpe:2.3:a:ruby-lang:ruby:2.7.0:preview1:*:*:*:*:*:*2.7.0 preview1Vulnerableruby
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*9.0VulnerableDebian
cpe:2.3:o:fedoraproject:fedora:30:*:*:*:*:*:*:*30VulnerableFedoraproject
cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*31VulnerableFedoraproject
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*32VulnerableFedoraproject
  • cpe:2.3:a:puma:puma:*:*:*:*:*:ruby:*:* Versions up to 3.12.3; 4.0.0 – 4.3.2 Vulnerable ·puma
  • cpe:2.3:a:ruby-lang:ruby:*:*:*:*:*:*:*:* Versions up to 2.3.0; 2.4.0 – 2.4.7; 2.5.0 – 2.5.6; 2.6.0 – 2.6.4 Vulnerable ·ruby
  • cpe:2.3:a:ruby-lang:ruby:2.7.0:preview1:*:*:*:*:*:* Versions 2.7.0 preview1 Vulnerable ·ruby
  • cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Debian
  • cpe:2.3:o:fedoraproject:fedora:30:*:*:*:*:*:*:* Versions 30 Vulnerable ·Fedoraproject
  • cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:* Versions 31 Vulnerable ·Fedoraproject
  • cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:* Versions 32 Vulnerable ·Fedoraproject

Remediation

  • Fix · CNA Puma (puma) Fixed in 3.12.3, 4.3.2
  • Fix · GHSA-84j7-475p-hp8v puma (RubyGems) Fixed in 3.12.4 Advisory →
  • Fix · GHSA-84j7-475p-hp8v puma (RubyGems) Fixed in 4.3.3 Advisory →

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Advisory ·

    Puma — FEDORA-2020-fd87f90634

    2 records Highest priority Priority LOW 2 LOW

    Other records, highest priority first

    • TI-2020-04305 HTTP Response Splitting (Early Hints) in PumaPriority LOW 32
    Show all 2 records → Advisory →
  • Advisory ·

    Puma — FEDORA-2020-08092b4c97

    2 records Highest priority Priority LOW 2 LOW

    Other records, highest priority first

    • TI-2020-04305 HTTP Response Splitting (Early Hints) in PumaPriority LOW 32
    Show all 2 records → Advisory →
Show 1 more group
  • Advisory ·

    Puma — FEDORA-2020-a3f26a9387

    2 records Highest priority Priority LOW 2 LOW

    Other records, highest priority first

    • TI-2020-04305 HTTP Response Splitting (Early Hints) in PumaPriority LOW 32
    Show all 2 records → Advisory →

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
CloudForms Management Engine 5AffectedNo fix planned: Will not fix
Red Hat 3scale API Management Platform 2AffectedNo fix yet
Red Hat Software CollectionsAffectedNo fix planned: Will not fix
Red Hat Storage 3AffectedNo fix planned: Will not fix

Timeline

  1. 2026-10-02 Threatist record created from CVE-2020-5247
  2. 2026-10-03 Alias added: GHSA-84j7-475p-hp8v

References

Advisory 8

Other 6

  • TI-2022-08603 HTTP Request Smuggling in puma CVSS 3.1CRITICAL 9.1
  • TI-2023-21048 Inconsistent Interpretation of HTTP Requests in puma CVSS 3.1CRITICAL 9.8
  • TI-2022-07686 Information Exposure when using Puma with Rails CVSS 3.1HIGH 8.0
  • TI-2020-08950 HTTP Smuggling via Transfer-Encoding Header in Puma CVSS 3.1HIGH 7.5
  • TI-2020-08951 HTTP Smuggling via Transfer-Encoding Header in Puma CVSS 3.1HIGH 7.5
  • TI-2019-12551 Potential DOS attack in Puma CVSS 3.1HIGH 7.5
See all 11 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences