C300 PCNT02: Deployment of Wrong Handler
CVE-2025-3946 is a high-severity deployment of wrong handler 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 0.55% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of C300 PCNT02 you run against the affected versions below, and install the vendor's latest release.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Honeywell | C300 PCNT02 | 520.1 through 520.2 TCU9; 530 through 530 TCU3 | Not stated |
| Honeywell | C300 PCNT05 | 520.1 through 520.2 TCU9; 530 through 530 TCU3 | Not stated |
| Honeywell | FIM4 | 520.1 through 520.2 TCU9; 530 through 530 TCU3 | Not stated |
| Honeywell | FIM8 | 520.1 through 520.2 TCU9; 530 through 530 TCU3 | Not stated |
| Honeywell | UOC | 520.1 through 520.2 TCU9; 530 through 530 TCU3 | Not stated |
| Honeywell | CN100 | 520.1 through 520.2 TCU9; 530 through 530 TCU3 | Not stated |
| Honeywell | HCA | 520.1 through 520.2 TCU9; 530 through 530 TCU3 | Not stated |
| Honeywell | C300PM | 520.1 through 520.2 TCU9; 530 through 530 TCU3 | Not stated |
| Honeywell | C200E | 520.1 through 520.2 TCU9; 530 through 530 TCU3 | Not stated |
| Honeywell | Wireless Device Manager | 322.1 through 322.4; 330.1 through 330.3 | Not 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 and OneWireless WDM contains a Deployment of Wrong Handler vulnerability in the component Control Data Access (CDA). An attacker could potentially exploit this vulnerability, leading to Input Data Manipulation, which could result in incorrect handling of packets leading to remote code execution. Honeywell recommends updating to the most recent version of Honeywell Experion PKS:520.2 TCU9 HF1 and 530.1 TCU3 HF1 and OneWireless: 322.5 and 331.1. 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. The OneWireless WDM affected versions are 322.1 through 322.4 and 330.1 through 330.3.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Deployment of Wrong Handler
The wrong handler is assigned to process an object or request.
How developers prevent this class of flaw
- Perform a type check before interpreting an object.
- Reject any inconsistent types, such as a file with a.GIF extension that appears to consist of PHP code.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in C300 PCNT02
- 8.2 High severity
- 9.4 Critical severity
- 8.6 High severity
- 7.5 High severity
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