CVE-2025-51986Public exploitNetwork attack vector

Remote service hang via unchecked packet length

Published Aug 14, 2025 · Updated Aug 14, 2025

Denial of service in SILA Embedded Solutions GmbH freemodbus 2018-09-12 allows remote attackers to hang the LINUXTCP demo with a crafted packet. The xMBPortTCPPool function accepts a Modbus/TCP length field larger than the bytes that follow and repeatedly polls for bytes that never arrive. The flaw requires only network access to the listening service and lets an unauthenticated client occupy the sole client connection, preventing request processing.

CVSS severity7.5
High
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in SILA Embedded Solutions GmbH freemodbus 2018-09-12 allows remote attackers to hang the LINUXTCP demo with a crafted packet. The xMBPortTCPPool function accepts a Modbus/TCP length field larger than the bytes that follow and repeatedly polls for bytes that never arrive. The flaw requires only network access to the listening service and lets an unauthenticated client occupy the sole client connection, preventing request processing.

The record

CVE
CVE-2025-51986
Published
Aug 14, 2025
Updated
Aug 14, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-835, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 14, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 14, 2025Record 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 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 exploitPublished

Weakness, pattern, technique

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499.004Endpoint Denial of Service: Application or System Exploitation

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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