High severity · published Jul 14, 2026
CVE-2026-47737
Puma PROXY Protocol v1 Accepts Repeated Protocol Headers on Persistent Connections
7.5
CVSS
0.2%
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, 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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 7% 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-2026-47737
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-47737
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/pull/3944
github.com
https://github.com/puma/puma/pull/3947
github.com
https://github.com/puma/puma/releases/tag/v7.2.1
github.com
https://github.com/puma/puma/releases/tag/v8.0.2
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