Trane HVAC Systems Controls Improper Neutralization of Input During Web Page Generation (CVE-2021-42534)

medium Tenable OT Security Plugin ID 501756


The remote OT asset is affected by a vulnerability.


The affected product's web application does not properly neutralize the input during webpage generation, which could allow an attacker to inject code in the input forms.

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The following text was originally created by the Cybersecurity and Infrastructure Security Agency (CISA). The original can be found at

Trane has identified the following specific mitigations for the affected products:

- Users upgrade Tracer SC controllers running firmware v3.8 and prior, to firmware v4.4 SP7 or higher. Users should contact a regional Trane office to install updated firmware or request additional information and reference Trane service database number HUB-207592.
- Tracer SC is no longer actively developed, tested, or sold. Tracer SC will be considered end-of-life on December 31, 2022. Trane recommends users identify a migration plan to replace the Tracer SC controller with the Tracer SC+ controller, which can function as a drop-in replacement for Tracer SC, providing significant security upgrades.

In addition to the specific recommendations above, Trane recommends the following best practices as an additional protection against this and other controller vulnerabilities:

- Restrict physical controller access to trained and trusted personnel.
- Isolate Tracer controls from other network devices using virtual local area networks (VLAN), and from the Internet using a firewall with no exposed inbound ports.
- Use secure remote access solutions such as Trane Connect Remote Access.
- Ensure user credentials are not shared and follow best practices for appropriate complexity (e.g., strong passwords).
- Have a well-documented process and owner to ensure regular software/firmware updates and to keep systems up to date.

See Also

Plugin Details

Severity: Medium

ID: 501756

Version: 1.5

Type: remote

Family: Tenable.ot

Published: 10/23/2023

Updated: 4/11/2024

Supported Sensors: Tenable OT Security

Risk Information


Risk Factor: Low

Score: 3.0


Risk Factor: Medium

Base Score: 4.3

Temporal Score: 3.2

Vector: CVSS2#AV:N/AC:M/Au:N/C:N/I:P/A:N

CVSS Score Source: CVE-2021-42534


Risk Factor: Medium

Base Score: 6.1

Temporal Score: 5.3

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:trane:tracer_sc_firmware

Required KB Items: Tenable.ot/Trane

Exploit Ease: No known exploits are available

Patch Publication Date: 10/22/2021

Vulnerability Publication Date: 10/22/2021

Reference Information

CVE: CVE-2021-42534

CWE: 79