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TI-2021-17975 Aliases CVE-2021-41136GHSA-48w2-rm65-62xx

Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling') in puma

Priority LOW 20CWE-444Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
Required
Attack complexity
High
Impact type
—
Confidentiality · integrity · availability
Low · Low · None
Fix status
Partial Red Hat: 2 fixed, 2 without a fix

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

Summary

Puma is a HTTP 1.1 server for Ruby/Rack applications. Prior to versions 5.5.1 and 4.3.9, using `puma` with a proxy which forwards HTTP header values which contain the LF character could allow HTTP request smugggling. A client could smuggle a request through a proxy, causing the proxy to send a response back to another unknown client. The only proxy which has this behavior, as far as the Puma team is aware of, is Apache Traffic Server. If the proxy uses persistent connections and the client adds another request in via HTTP pipelining, the proxy may mistake it as the first request's body. Puma, however, would see it as two requests, and when processing the second request, send back a response that the proxy does not expect. If the proxy has reused the persistent connection to Puma to send another request for a different client, the second response from the first client will be sent to the second client. This vulnerability was patched in Puma 5.5.1 and 4.3.9. As a workaround, do not use Apache Traffic Server with `puma`.

Why it matters now

EPSS 0.01203 68th percentileScored 2026-11-07
Fix Partial puma (puma): 5.5.1, 4.3.9puma (RubyGems): 5.5.1, 4.3.9Red Hat: 1 advisoryRed Hat: 2 fixed, 2 without a fix

SSVC decision points

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

Affected products

VendorProductAffected versionsFixed inStatusSource
pumapuma5.0.0 to before 5.5.1; before 4.3.95.5.1, 4.3.9Patch availableCNA
—puma (RubyGems)5.0.0 to before 5.5.15.5.1Patch availableGHSA-48w2-rm65-62xx
—puma (RubyGems)before 4.3.94.3.9Patch availableGHSA-48w2-rm65-62xx
  • puma Vendorpuma Affected 5.0.0 to before 5.5.1; before 4.3.9 Fixed in 5.5.1, 4.3.9 Patch available CNA
  • puma (RubyGems) Vendor— Affected 5.0.0 to before 5.5.1 Fixed in 5.5.1 Patch available GHSA-48w2-rm65-62xx
  • puma (RubyGems) Vendor— Affected before 4.3.9 Fixed in 4.3.9 Patch available GHSA-48w2-rm65-62xx

CPE configurations NVD · 3

CPEVersionsRoleVendor
cpe:2.3:a:puma:puma:*:*:*:*:*:ruby:*:*up to 4.3.8; 5.0.0 – 5.5.0Vulnerablepuma
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*10.0VulnerableDebian
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*11.0VulnerableDebian
  • cpe:2.3:a:puma:puma:*:*:*:*:*:ruby:*:* Versions up to 4.3.8; 5.0.0 – 5.5.0 Vulnerable ·puma
  • cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* Versions 10.0 Vulnerable ·Debian
  • cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* Versions 11.0 Vulnerable ·Debian

Remediation

  • Fix · CNA puma (puma) Fixed in 5.5.1, 4.3.9
  • Fix · GHSA-48w2-rm65-62xx puma (RubyGems) Fixed in 5.5.1 Advisory →
  • Fix · GHSA-48w2-rm65-62xx puma (RubyGems) Fixed in 4.3.9 Advisory →

Red Hat 1 advisory

  • RHSA-2022:5498 Released 2022-07-05 · Red Hat rating Moderate
    Satellite 6.11 Release
    • Red Hat Satellite 6.11 for RHEL 7 candlepin-4.1.13-1.el7sat, foreman-3.1.1.21-2.el7sat, libsolv-0.7.22-1.el7pc +4
    • Red Hat Satellite 6.11 for RHEL 8 candlepin-4.1.13-1.el8sat, foreman-3.1.1.21-2.el8sat, libsolv-0.7.22-1.el8pc +8

Vendor assessments

Red Hat

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

ProductStatusPlan or fix
CloudForms Management Engine 5AffectedNo fix planned: Will not fix
Red Hat Storage 3AffectedNo fix yet: Fix deferred
Red Hat Satellite 6.11 for RHEL 7Fixed RHSA-2022:5498
Red Hat Satellite 6.11 for RHEL 8Fixed RHSA-2022:5498
Not affected: 2 products
  • Red Hat Satellite 6.11 for RHEL 7
  • Red Hat Satellite 6.11 for RHEL 8

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-41136
  2. 2026-10-03 Alias added: GHSA-48w2-rm65-62xx

References

Patch 1

Advisory 5

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-2020-04303 HTTP Response Splitting 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