Is CVE-2026-47736 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-47736 being exploited in the wild.

How severe is CVE-2026-47736?

High severity, with a CVSS score of 7.5, published 14 July 2026.

Which products and versions are affected?

puma (RubyGems) ECOSYSTEM:introduced=8.0.0,fixed=8.0.2.

Is there a fix for CVE-2026-47736?

Yes. puma (RubyGems): upgrade to 8.0.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-47736 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-47736?

Check whether you run puma (RubyGems) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-47736: Puma uncontrolled resource consumption in PROXY protocol v1 parser

CVE-2026-47736 · Severity: high · CVSS 7.5 · Published 2026-07-14

Puma is a popular web server used to run Ruby applications. A vulnerability in its handling of the PROXY protocol allows an attacker to crash the server or significantly slow it down by sending a continuous stream of data without the expected line endings. This can lead to a total service outage (denial of service) as the server consumes all available memory and processor power trying to process the malicious request.

Technologies: puma (RubyGems). Vendors: RubyGems.

Quick answers

Is CVE-2026-47736 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-47736 being exploited in the wild.
How severe is CVE-2026-47736?: High severity, with a CVSS score of 7.5, published 14 July 2026.
Which products and versions are affected?: puma (RubyGems) ECOSYSTEM:introduced=8.0.0,fixed=8.0.2.
Is there a fix for CVE-2026-47736?: Yes. puma (RubyGems): upgrade to 8.0.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-47736 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-47736?: Check whether you run puma (RubyGems) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

puma (RubyGems): upgrade to 8.0.2 or later
```
bundle update puma
```

Technical details

Puma is vulnerable to uncontrolled resource consumption (CWE-400) within its PROXY protocol v1 parsing logic. When the 'proxy_protocol: :v1' configuration is enabled, the server reads incoming bytes into an internal pre-parse buffer while searching for a CRLF (\r\n) sequence. Because there is no limit on the size of this buffer before the CRLF is found, a remote, unauthenticated attacker can establish a TCP connection and send a continuous stream of bytes without line endings. This results in unbounded memory growth and high CPU usage as the server repeatedly scans the ever-increasing buffer. The vulnerability is resolved in versions 7.2.1 and 8.0.2 by enforcing maximum line lengths and anchoring the protocol regex.

Affected products

Puma Puma >= 5.5.0, < 7.2.1; >= 8.0.0, < 8.0.2

Identifiers

CVE-2026-47736
GHSA-qpgp-93vx-g8v8

Timeline

2026-05-27: advisory: GitHub Security Advisory published
2026-05-27: patched: Versions 7.2.1 and 8.0.2 released
2026-07-14: disclosed: CVE-2026-47736 published to NVD

References

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