High severity · published Jul 14, 2026
CVE-2026-47736
Puma PROXY Protocol v1 Parser Allows Remote Memory Exhaustion
7.5
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 28% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
PU
puma · puma
>= 5.5.0, < 7.2.1; >= 8.0.0, < 8.0.2 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-47736
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-47736
github.com
https://github.com/puma/puma/commit/439c6136d9c2275721b7864db3ee78af7c80889f
github.com
https://github.com/puma/puma/commit/ebe9db3929ab8299d19c8f5b41e8ef4f4b22fa58
github.com
https://github.com/puma/puma/releases/tag/v7.2.1
github.com
https://github.com/puma/puma/releases/tag/v8.0.2
github.com
https://github.com/puma/puma/security/advisories/GHSA-qpgp-93vx-g8v8
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