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Fencer Vulns
high 7.5

CVE-2026-47737 json

Puma PROXY Protocol v1 Accepts Repeated Protocol Headers on Persistent Connections

published 2026-06-09 5 mo ago modified 2026-11-02 6 d ago also GHSA-2vqw-3mp8-cgmx , EUVD-2026-44427

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

debian advisories DEBIAN-CVE-2026-47737

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
3 mo ago

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-08).

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 Vulns 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.