CyberSecBulletin
CVE-2025-3947NVD status: Deferred

C300 PCNT02: Integer Underflow (Wrap or Wraparound)

Published Updated By the CyberSecBulletin desk

CVE-2025-3947 is a high-severity integer underflow (wrap or wraparound) vulnerability in C300 PCNT02 from Honeywell, with a CVSS 3.1 base score of 8.2 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected C300 PCNT02 versions: 520.1 through 520.2 TCU9; 530 through 530 TCU3. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.37% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of C300 PCNT02 you run against the affected versions below, and install the vendor's latest release.
  2. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
HoneywellC300 PCNT02520.1 through 520.2 TCU9; 530 through 530 TCU3Not stated
HoneywellC300 PCNT05520.1 through 520.2 TCU9; 530 through 530 TCU3Not stated
HoneywellFIM4520.1 through 520.2 TCU9; 530 through 530 TCU3Not stated
HoneywellFIM8520.1 through 520.2 TCU9; 530 through 530 TCU3Not stated
HoneywellUOC520.1 through 520.2 TCU9; 530 through 530 TCU3Not stated
HoneywellCN100520.1 through 520.2 TCU9; 530 through 530 TCU3Not stated
HoneywellHCA520.1 through 520.2 TCU9; 530 through 530 TCU3Not stated
HoneywellC300PM520.1 through 520.2 TCU9; 530 through 530 TCU3Not stated
HoneywellC200E520.1 through 520.2 TCU9; 530 through 530 TCU3Not stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
LowLimited modification of data is possible.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H. Scored by CNA (honeywell.com).

Official description

The Honeywell Experion PKS contains an Integer Underflow vulnerability in the component Control Data Access (CDA). An attacker could potentially exploit this vulnerability, leading to Input Data Manipulation, which could result in improper integer data value checking during subtraction leading to a denial of service. Honeywell recommends updating to the most recent version of Honeywell Experion PKS:520.2 TCU9 HF1 and 530.1 TCU3 HF1. The affected Experion PKS products are C300 PCNT02, C300 PCNT05, FIM4, FIM8, UOC, CN100, HCA, C300PM, and C200E. The Experion PKS versions affected are from 520.1 through 520.2 TCU9 and from 530 through 530 TCU3.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Integer Underflow (Wrap or Wraparound)

The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.

More Integer Underflow (Wrap or Wraparound) vulnerabilities (CWE-191)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other references

Other vulnerabilities in C300 PCNT02

All C300 PCNT02 vulnerabilities

Recent Integer Underflow (Wrap or Wraparound) vulnerabilities

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