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Fencer Vulns
high 7.5

CVE-2026-47736 json

Puma PROXY Protocol v1 Parser Allows Remote Memory Exhaustion

published 2026-06-08 5 mo ago modified 2026-11-02 6 d ago also GHSA-qpgp-93vx-g8v8 , EUVD-2026-44442

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 28%
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, when PROXY protocol v1 support is enabled, Puma reads incoming bytes into an internal buffer while waiting for CRLF to determine whether a PROXY v1 line is present, allowing an attacker that continuously sends bytes without CRLF to cause unbounded in-process memory growth and additional CPU cost from repeatedly scanning the growing buffer. 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-2026-47736

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-2026-47736 updated cvss 7.5

puma: Puma: Denial of Service due to unbounded memory growth in PROXY protocol v1

  • 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
    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

0.35% chance of exploitation in the next 30 days, higher than 28% 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:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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-400 Uncontrolled Resource Consumption

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.