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Fencer Intel
high 7.5

CVE-2026-47737 json

Puma PROXY Protocol v1 Accepts Repeated Protocol Headers on Persistent Connections

published 5mo ago modified 9d ago also EUVD-2026-44427 , GHSA-2vqw-3mp8-cgmx

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits
0
none known

Summary

Puma is a Ruby/Rack web server built for parallelism. From 5.5.0 until 7.2.1 and 8.0.2, Puma is vulnerable to source IP spoofing when set_remote_address proxy_protocol: :v1 is enabled and persistent connections are used because Puma incorrectly re-parses PROXY protocol headers after each keep-alive request on the same connection, allowing an attacker to inject a second PROXY header and overwrite REMOTE_ADDR. This issue is fixed in versions 7.2.1 and 8.0.2.

Patch / fix

  • rubygems puma 7.2.1, 8.0.2
  • puma puma 7.2.1, 8.0.2
  • puma Debian 12 5.6.5-3+deb12u2
  • puma Debian 14 8.0.2-1

debian advisories DEBIAN-CVE-2026-47737

Is CVE-2026-47737 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-47737 updated cvss 7.5

puma: Puma: Source IP spoofing via PROXY protocol header re-parsing

  • Red Hat 3scale API Management Platform 2 3scale-amp21/zync, 3scale-amp22/zync, 3scale-amp21/backend, 3scale-amp22/backend, 3scale-amp2/zync-rhel8, 3scale-amp2/zync-rhel9, +1 more Red Hat Enterprise Linux 8 pcs, pcs-snmp Red Hat Enterprise Linux 9 pcs, pcs-snmp Red Hat Enterprise Linux 10 pcs Red Hat Satellite 6 rubygem-puma, rubygem-puma 6.4.3-1.el8sat
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
3mo ago

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected packages

ecosystem package affected fixed in
rubygems puma
>=8.0.0, <8.0.2
>=5.5.0, <7.2.1
8.0.2
7.2.1

Affected products

  • puma puma

Classification

Weakness
  • CWE-290 Authentication Bypass by Spoofing
  • CWE-345 Insufficient Verification of Data Authenticity

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.