CVE-2025-61736: iSTAR- Improper Validation of Certificate Expiration

Published Dec 17, 2025
·
Updated

Successful exploitation of this vulnerability could result in the product failing to re-establish communication once the certificate expires.

Affected Software

5 affected components
: Johnson Controls Inc. iSTAR eX: All versions prior to TLS 1.2
: Johnson Controls Inc. iSTAR Edge: All versions prior to TLS 1.2
: Johnson Controls Inc. iSTAR Ultra LT (if in TLS 1.2): All versions prior to TLS 1.2
: Johnson Controls Inc. iSTAR Ultra (if in TLS 1.2): All versions prior to TLS 1.2
: Johnson Controls Inc. iSTAR Ultra SE (if in TLS 1.2): All versions prior to TLS 1.2

Remediation

Information

Johnson Controls recommends the following mitigations: Host-based certificates using TLS 1.2: * Quickest solution * No Upgrade required to specific C•CURE or iSTAR software/firmware versions * Requires downloading a new certificate to all iSTAR panels simultaneously, resulting in a brief system downtime Convert encryption mode to TLS 1.3, per cluster: * Requires firmware 6.9.0 or higher, and C•CURE 9000 v2.90 SP3 or higher * Enables phased implementation by cluster, minimizing disruption * Note: TLS 1.3 is not supported on iSTAR eX, iSTAR Edge, and iSTAR Ultra LT panels Upgrade legacy panels to new G2 hardware: * Recommended for smaller systems due to time constraints * Applies primarily to iSTAR eX, iSTAR Edge, and iSTAR LT panels

Event History

Dec 17, 2025
CVE Published
via MITRE·12:36 PM
Data Sourced
via MITRE·12:36 PM
RemedyDescriptionWeakness
Data Sourced
via ICS·01:00 PM
SeverityWeaknessAffected Software
Data Sourced
via NVD·01:15 PM
DescriptionSeverityWeakness

Parent advisories

This vulnerability appears in the following advisories.

Frequently Asked Questions

1

What is the severity of CVE-2025-61736?

CVE-2025-61736 is categorized as a high severity vulnerability due to the risk of failed communication after certificate expiration.

2

How do I fix CVE-2025-61736?

To fix CVE-2025-61736, ensure that you upgrade to the latest version of the affected Johnson Controls products that support TLS 1.2.

3

What products are affected by CVE-2025-61736?

CVE-2025-61736 affects Johnson Controls iSTAR eX, iSTAR Edge, iSTAR Ultra LT, iSTAR Ultra, and iSTAR Ultra SE models prior to TLS 1.2.

4

What happens if CVE-2025-61736 is exploited?

Exploitation of CVE-2025-61736 can lead to a failure in re-establishing communication once the product's certificate expires.

5

Is there a temporary workaround for CVE-2025-61736?

Currently, there are no documented temporary workarounds for CVE-2025-61736, and upgrading to a secure version is recommended.

Company

Resources

Contact

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