CVE-2026-47737: Puma

High severity, CVSS 7.5. EPSS: 0.2% chance of exploitation in the next 30 days.

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.

Affected products

• Puma Puma: from 5.5.0, before 7.2.1 (fixed in 7.2.1); from 8.0.0, before 8.0.2 (fixed in 8.0.2)

Published 2026-07-14. Last modified 2026-07-15.