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Vulnerability · Published Jul 14, 2026 · Assigned by GitHub_M

CVE-2026-47736Puma PROXY Protocol v1 Parser Allows Remote Memory Exhaustion

High 7.5

In plain English

A high-severity uncontrolled resource consumption in puma from puma. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 28% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.3%top 71.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12puma5.6.5-3+deb12u2DEBIAN-CVE-2026-47736
Debian:13pumano fix listedDEBIAN-CVE-2026-47736
Debian:14puma8.0.2-1DEBIAN-CVE-2026-47736
RubyGemspuma7.2.1GHSA-qpgp-93vx-g8v8
RubyGemspuma8.0.2GHSA-qpgp-93vx-g8v8
Ubuntu:24.04:LTSpumano fix listedUBUNTU-CVE-2026-47736
Ubuntu:26.04:LTSpumano fix listedUBUNTU-CVE-2026-47736
Ubuntu:26.10pumano fix listedUBUNTU-CVE-2026-47736

Affected products (as reported)

VendorProductVersions
puma puma >= 5.5.0, < 7.2.1>= 8.0.0, < 8.0.2

Weakness: CWE-400 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References