CVE-2025-56352Public exploitNetwork attack vector

Unauthenticated service interrupt via unclosed CONNECT sockets

Published May 18, 2026 · Updated May 18, 2026

Uncontrolled resource consumption in tinyMQTT commit 6226ade allows remote attackers to cause a broker service interrupt via malformed CONNECT packets. The parse_connect_packet function sends Identifier Rejected for a zero-length Client ID with CleanSession set to 0 but returns without ensuring TCP socket closure. Repeated unauthenticated connections retain file descriptors and memory until the broker refuses new clients or becomes unresponsive.

CVSS severity7.5
High
EPSS probability0.28%
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 tinyMQTT commit 6226ade allows remote attackers to cause a broker service interrupt via malformed CONNECT packets. The parse_connect_packet function sends Identifier Rejected for a zero-length Client ID with CleanSession set to 0 but returns without ensuring TCP socket closure. Repeated unauthenticated connections retain file descriptors and memory until the broker refuses new clients or becomes unresponsive.

The record

CVE
CVE-2025-56352
Published
May 18, 2026
Updated
May 18, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-400, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 18, 2026CVE publishedPublication date reported by the CVE source.
  2. May 18, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5CISA-ADPCVSS: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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499.003Application Exhaustion Flood

Public exploit references

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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