EUVD-2025-21068CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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3Description
The Honeywell Experion PKS contains an Uninitialized Variable in the common Epic Platform Analyzer (EPA) communications. An attacker could potentially exploit this vulnerability, leading to a Communication Channel Manipulation, which results in a dereferencing of an uninitialized pointer leading to a denial of service. Honeywell recommends updating to the most recent version of Honeywell Experion PKS: 520.2 TCU9 HF1and 530.1 TCU3 HF1. The affected Experion PKS products are C300 PCNT02, EHB, EHPM, ELMM, Classic ENIM, ETN, FIM4, FIM8, PGM, and RFIM. The Experion PKS versions affected are from 520.1 through 520.2 TCU9 and from 530 through 530 TCU3.
Analysis
CVE-2025-2520 is an uninitialized variable vulnerability in Honeywell Experion PKS's Epic Platform Analyzer (EPA) communications module that enables remote attackers to manipulate communication channels and trigger pointer dereference errors, resulting in denial of service. The vulnerability affects multiple Experion PKS product lines across versions 520.1-520.2 TCU9 and 530-530 TCU3, with a CVSS score of 7.5 indicating high availability impact. No evidence of active exploitation (KEV status) or public POC availability is indicated; however, the network-accessible attack vector and lack of authentication requirements elevate real-world risk for critical industrial control environments.
Technical Context
The vulnerability resides in the Epic Platform Analyzer (EPA) communications subsystem of Honeywell Experion PKS, a distributed process control system used in industrial automation. The root cause is classified under CWE-457 (Use of Uninitialized Variable), where the EPA communications handler fails to initialize a variable before use in the common communication protocol stack. When an attacker sends a specially crafted network packet to the EPA communications interface, the uninitialized variable is dereferenced within the channel manipulation logic, causing a null or garbage pointer dereference. This occurs in the communication channel state machine, which processes incoming requests without proper input validation or variable initialization checks. The affected products include C300 PCNT02, EHB, EHPM, ELMM, Classic ENIM, ETN, FIM4, FIM8, PGM, and RFIM modules, all of which implement the compromised EPA protocol handler. The vulnerability is network-exploitable (AV:N) with low attack complexity (AC:L) and requires no prior authentication (PR:N) or user interaction (UI:N), making it accessible to unauthenticated remote adversaries.
Affected Products
Honeywell Experion PKS versions 520.1 through 520.2 TCU9 and 530 through 530 TCU3 are affected. Specific product lines impacted include: C300 PCNT02, EHB (Ethernet Highway Bridge), EHPM (Ethernet High-Speed Port Module), ELMM (Ethernet Local Maintenance Module), Classic ENIM (Ethernet Network Interface Module), ETN (Ethernet Terminal Node), FIM4 (Four-Channel Field Interface Module), FIM8 (Eight-Channel Field Interface Module), PGM (Programmable Gateway Module), and RFIM (Remote Field Interface Module). Remediation is available via: Honeywell Experion PKS 520.2 TCU9 HF1 (for 520.x line) and Honeywell Experion PKS 530.1 TCU3 HF1 (for 530.x line). Organizations should consult the official Honeywell Security Advisory for CVE-2025-2520 and cross-reference their installed product configurations against the affected product list to determine exposure.
Remediation
Immediate action: upgrade to patched versions Honeywell Experion PKS 520.2 TCU9 HF1 or 530.1 TCU3 HF1 depending on your installed version. Before patching, implement network-level mitigations: (1) restrict network access to EPA communication ports using firewall rules to only trusted engineering workstations and control systems; (2) implement network segmentation to isolate Experion PKS systems from untrusted networks; (3) disable EPA communications if not in active use. Post-patch validation: test communication channel integrity after upgrade to verify EPA stability. For organizations unable to patch immediately, apply compensating controls via industrial firewalls to block unexpected EPA protocol traffic and monitor for abnormal communication patterns. Honeywell's official security advisory should be consulted for detailed patch deployment procedures and any additional workarounds specific to your configuration.
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