CVE-2026-47736

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of service disruption.

Exploit odds

0.3% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-07-14 20:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-07-15 18:15 UTC Last updatedMost recent change to the record

Details

Published

2026-07-14 20:17 UTC

Last modified

2026-07-15 18:15 UTC

Exploit probability

0.3% · EPSS, next 30 days

Weakness

CWE-400 · Uncontrolled resource consumption

Record status

Deferred

Attack profile CVSS 3.1 · 7.5

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High