CVE-2025-41704Public exploitNetwork attack vector

Unauthenticated Modbus service hang via diagnostic query

Published Oct 14, 2025 · Updated Oct 14, 2025

Resource exhaustion in Phoenix Contact QUINT4-UPS EIP firmware before VC:07 allows remote attackers to hang the Modbus service. The Modbus/TCP diagnostic handler accepts function 0x08 with subfunction 0x0000 and then stops processing or answering later requests. A single unauthenticated network request is sufficient; the UPS core continues operating, but subsequent Modbus control and monitoring traffic is blocked.

CVSS severity5.3
Medium
EPSS probability1.59%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Phoenix Contact QUINT4-UPS EIP firmware before VC:07 allows remote attackers to hang the Modbus service. The Modbus/TCP diagnostic handler accepts function 0x08 with subfunction 0x0000 and then stops processing or answering later requests. A single unauthenticated network request is sufficient; the UPS core continues operating, but subsequent Modbus control and monitoring traffic is blocked.

The record

CVE
CVE-2025-41704
Published
Oct 14, 2025
Updated
Oct 14, 2025
Vendor
Phoenix Contact
Product
QUINT4-UPS/24DC/24DC/20/EIP
Classifications
CWE-770, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 14, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 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?

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

  1. Affected versionversion=VC:00 <VC:07

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Phoenix Contact · QUINT4-UPS/24DC/24DC/20/EIPversion=VC:00 <VC:07
Phoenix Contact · QUINT4-UPS/24DC/24DC/5/EIPversion=VC:00 <VC:07
Phoenix Contact · QUINT4-UPS/24DC/24DC/40/EIPversion=VC:00 <VC:07
Phoenix Contact · QUINT4-UPS/24DC/24DC/10/EIPversion=VC:00 <VC:07

Published CVSS scores

5.3CERT VDECVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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-770Allocation of Resources Without Limits or Throttling
T1499Endpoint Denial of Service

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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