puma: Puma is a Ruby/Rack web server built for parallelism
CVE-2026-47736 is fixed in puma on 1 platform, first by DEBIAN-CVE-2026-47736, released July 18, 2026. It is not reported as exploited. Patch Radar priority: High.
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.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| puma · Debian 12.15 (bookworm) | 5.6.5-3+deb12u2 | DEBIAN-CVE-2026-47736 | Jul 18, 2026 |
| puma · Debian 14 | 8.0.2-1 | DEBIAN-CVE-2026-47736 | Jul 18, 2026 |
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