CVE-2026-47736Network attack vector

Remote memory exhaustion via unterminated PROXY header

Published Jul 14, 2026 · Updated Jul 14, 2026

Uncontrolled resource consumption in Puma 5.5.0 through 7.2.0 and 8.0.0 through 8.0.1 allows remote attackers to exhaust memory. The try_to_parse_proxy_protocol method in lib/puma/client.rb appends TCP bytes to an internal buffer and repeatedly searches for CRLF without enforcing a line-length limit. A single unauthenticated TCP connection can exhaust a process or container, but only when the non-default PROXY protocol v1 setting is enabled.

CVSS severity7.5
High
EPSS probability0.63%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled resource consumption in Puma 5.5.0 through 7.2.0 and 8.0.0 through 8.0.1 allows remote attackers to exhaust memory. The try_to_parse_proxy_protocol method in lib/puma/client.rb appends TCP bytes to an internal buffer and repeatedly searches for CRLF without enforcing a line-length limit. A single unauthenticated TCP connection can exhaust a process or container, but only when the non-default PROXY protocol v1 setting is enabled.

The record

CVE
CVE-2026-47736
Published
Jul 14, 2026
Updated
Jul 14, 2026
Vendor
Puma
Product
Puma
Classifications
CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 5.5.0, < 7.2.1
  2. Affected versionversion=>= 8.0.0, < 8.0.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Puma · Pumaversion=>= 5.5.0, < 7.2.1; version=>= 8.0.0, < 8.0.2

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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