CVE-2025-56352
📛 CVE Title
CVE-2025-56352
Description
In tinyMQTT commit 6226ade15bd4f97be2d196352e64dd10937c1962 (2024-02-18), the broker mishandles protocol violations during CONNECT packet parsing. When receiving a CONNECT packet with a zero-length Client ID while CleanSession is set to 0, the broker correctly replies with a CONNACK return code 0x02 (Identifier Rejected) but fails to explicitly close the TCP connection. Since the surrounding connection teardown logic is not guaranteed to execute, each such invalid CONNECT attempt leaves the underlying socket open. Repeated attempts cause server-side resource exhaustion due to accumulating file descriptors and memory usage, potentially resulting in denial of service.
Overview
- State
- PUBLISHED
- Assigner (CNA)
- mitre
- CVSS severity
- high
- CVSS score
- 7.5 / 10
- CVSS vector
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Effective score
- 7.5 / 10 HIGH source: CNA overview
- CWE(s)
- —
- Reserved
- 2025-08-16
- Published
- 2026-05-18 00:00 UTC
- Last updated
- 2026-05-18 17:27 UTC
- Source
- https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2025/56xxx/CVE-2025-56352.json
- Linked Threat
- CVE-2025-56352 — CVE-2025-56352
NVD triage scoring NVD CVE 2.0
Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.
- NVD published
- 2026-05-18 16:16:29 UTC
- NVD last modified
- 2026-05-18 20:27:23 UTC
- NVD CVSS v3.1
- 7.5 / 10 HIGH source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
- NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Exploitability subscore
- 3.9 / 10
- Impact subscore
- 3.6 / 10
- EPSS score
- 0.0007 (probability of exploitation in next 30 days)
- EPSS percentile
- 20.76% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24
NVD-assigned CWE(s):
CWE-400
(differs from the CNA list above)
NVD / KEV / EPSS data refreshed 2026-05-25 00:30 UTC. Re-run the 🛰 Backfill from NVD button above to refresh.
European Union Vulnerability Database ENISA EUVD
ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.
- EUVD ID
-
EUVD-2025-209887 - Assigner
- mitre
- Published
- May 18, 2026, 12:00:00 AM
- Updated
- May 18, 2026, 5:27:28 PM
- EUVD base score (CVSS 3.1)
-
7.5 / 10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - EUVD-reported EPSS
- 0.0700
- Vendors
- n/a
- Products
-
n/a (n/a)
- Aliases
-
GHSA-m5jh-ppcv-76xr
ENISA description: In tinyMQTT commit 6226ade15bd4f97be2d196352e64dd10937c1962 (2024-02-18), the broker mishandles protocol violations during CONNECT packet parsing. When receiving a CONNECT packet with a zero-length Client ID while CleanSession is set to 0, the broker correctly replies with a CONNACK return code 0x02 (Identifier Rejected) but fails to explicitly close the TCP connection. Since the surrounding connection teardown logic is not guaranteed to execute, each such invalid CONNECT attempt leaves the underlying socket open. Repeated attempts cause server-side resource exhaustion due to accumulating file descriptors and memory usage, potentially resulting in denial of service.
EUVD references (1)
Affected products (1)
| Vendor | Product | Versions | Platforms |
|---|---|---|---|
| n/a | n/a |
n/a (affected)
|
— |
Vendor references (1)
References embedded in the original CVE record by the assigning CNA.
Web references (5)
DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.
- https://github.com/JustDoIt0910/tinyMQTT/issues/19 tenable:github.com
- https://github.com/user-attachments/files/21207896/Resource_Exhaustion_Poc.txt tenable:github.com
- https://nvd.nist.gov/vuln/detail/CVE-2025-56352 tenable:nvd.nist.gov
- https://www.cve.org/CVERecord?id=CVE-2025-56352 tenable:www.cve.org
- https://www.first.org/epss/ tenable:www.first.org
NVD-tagged references (2)
Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.
- https://github.com/JustDoIt0910/tinyMQTT/issues/19 cve@mitre.org
- https://github.com/user-attachments/files/21207896/Resource_Exhaustion_Poc.txt 134c704f-9b21-4f2e-91b3-4a467353bcc0
Remediations (19)
Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.
-
web:cisa.gov
Update (08/12/ 2025 ): CISA has updated this alert to provide clarification on identifying Exchange Servers on an organization's networks and provided further guidance on running the Microsoft Exchange Health Checker. Update (08/07/ 2025 ): CISA issued Emergency Directive (ED) 25-02: Mitigate Microsoft Exchange Vulnerability in response to CVE - 2025 -53786
2026-05-23 22:19 UTC -
web:cve.akaoma.com
With low attack complexity and no required privileges, CVE-2025-56352 is an easy target for cybercriminals. Organizations should prioritize immediate mitigation measures to prevent unauthorized access and data breaches.
2026-05-23 22:19 UTC -
web:dailysecurityreview.com
Citrix warns that patches for critical NetScaler flaws may cause broken logins due to CSP conflicts. Admins must disable headers and clear cache to restore access.
2026-05-23 22:19 UTC -
web:feedly.com
CVE ID : CVE-2025-56352 Published : May 18, 2026, 4:16 p.m. 58 minutes ago Description : In tinyMQTT commit 6226ade15bd4f97be2d196352e64dd10937c1962 (2024-02-18), the broker mishandles protocol violations during CONNECT packet parsing.
2026-05-23 22:19 UTC -
web:krebsonsecurity.com
The reason is that after the Patch Tuesday on October 14, 2025 , Microsoft will stop shipping free security updates for Windows 10 computers.
2026-05-23 22:19 UTC -
web:portal.msrc.microsoft.com
The Security Update Guide provides information on the latest Microsoft security updates, helping users understand and address potential vulnerabilities effectively.
2026-05-23 22:19 UTC -
web:www.crowdstrike.com
Microsoft has released security updates for 107 vulnerabilities, including one publicly disclosed zero-day and 13 critical, in its August 2025 Patch Tuesday rollout.
2026-05-23 22:19 UTC -
web:www.nist.gov
NIST maintains the National Vulnerability Database (NVD), a repository of information on software and hardware flaws that can compromise computer security. This is a key piece of the nation's cybersecurity infrastructure.
2026-05-23 22:19 UTC -
web:www.thehackerwire.com
CVE-2025-56352 is a High severity vulnerability (CVSS 7.5). In tinyMQTT commit 6226ade15bd4f97be2d196352e64dd10937c1962 (2024-02-18), the broker mishandles protocol violations during CONNECT packet parsing.
2026-05-23 22:19 UTC -
web:zecurit.com
Get the complete breakdown of Microsoft's May 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .
2026-05-23 22:19 UTC -
web:community.ui.com
Published: May 21, 2026 Updated: May 22, 2026 Version: 1.1 Revision: 1.1 Summary 1 of 5 A malicious actor with access to the network and high privileges could exploit an Improper Input Validation vulnerability found in UniFi OS devices to execute a Command Injection. Affected Products: UniFi OS Server (Version 5.0.6 and earlier) Mitigation : Update your UniFi OS Server to Version 5.0.8 or later ...
2026-05-26 02:54 UTC -
web:www.bleepingcomputer.com
Microsoft has released out-of-band (OOB) security updates to patch a critical-severity Windows Server Update Service (WSUS) vulnerability with publicly available proof-of-concept exploit code.
2026-05-26 02:54 UTC -
web:www.cisa.gov
Updated October 29, 2025 : CISA has updated this Alert to include revised information on vulnerable product identification, potential threat activity detections, and additional resources. Microsoft released an update to address a critical remote code execution vulnerability impacting Windows Server Update Service (WSUS) in Windows Server (2012, 2016, 2019, 2022, and 2025 ), CVE - 2025 -59287
2026-05-26 02:54 UTC -
web:www.computerworld.com
Each month, the team at Readiness analyzes the latest Patch Tuesday updates from Microsoft and provides detailed, actionable testing guidance. The company's Patch Tuesday release for February ...
2026-05-26 02:54 UTC -
web:www.esri.com
Key highlights The ArcGIS Server Security 2025 update 2 is available This patch resolves 10 Medium severity vulnerabilities This security patch is cumulative, and includes fixes provided in the ArcGIS Server Security 2025 update 1.
2026-05-26 02:54 UTC -
web:www.oracle.com
Critical Security Patch Updates Critical Security Patch Updates provide security patches for supported Oracle on-premises products. A Critical Security Patch Update provides targeted, high-priority security fixes in a smaller, more focused format, making them easier to apply with minimal disruption.
2026-05-26 02:54 UTC -
web:www.rapid7.com
Microsoft has published 172 new vulnerabilities, including six zero-day vulnerabilities. Windows 10 moves past the end of support, sort of. Critical RCE in Windows Server Update Service.
2026-05-26 02:54 UTC -
web:www.tenable.com
Microsoft September 2025 Patch Tuesday addresses 80 CVEs including a Windows SMB flaw ( CVE - 2025 -55234) that was publicly disclosed.
2026-05-26 02:54 UTC -
web:www.virustotal.com
Streamline your investigations with Google Threat Intelligence Agentic and the new Dark Web (DDW) module. Perform hunting and pivoting across forums using natural language or specific modifiers. Bridge threat actor identities and map global operations easy.
2026-05-26 02:54 UTC
AI Forensic Analysis
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Raw JSON
The full cvelistV5 record. Download as CVE-2025-56352.json.
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