CVE-2026-20757 Gallagher CVE debrief

Who should care

Operators and administrators of Gallagher Command Centre Server instances should be aware of this vulnerability and take steps to mitigate it. This includes assessing their exposure, applying patches, and implementing compensating controls such as network segmentation and access controls. Security teams should review compensating controls for exposed systems while remediation is scheduled and verified, and track exceptions, retest remediated assets, and close the item only after evidence is documented. Vulnerability management teams should confirm whether affected product deployments exist in managed environments and assign an owner for follow-up. IT teams should plan vendor-supported updates or mitigations through normal change control where exposure is confirmed. Monitoring and detection teams should check relevant monitoring, detection, and logs for exposed assets that need extra review. Asset inventory managers should inventory and assess Gallagher Command Centre Server instances for exposure and apply patches. Incident response teams should update incident response plans to include procedures for potential denial-of-service attacks. System administrators should verify vendor-supplied patches and apply them. Change management teams should review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance. Source tracking should be implemented to monitor for any updates or changes related to this vulnerability. To address this vulnerability, operators should prioritize patching Gallagher Command Centre Server instances, especially those with internet-exposed management interfaces, to prevent potential limited denial-of-service attacks. Gallagher Command Centre Server instances with internet-exposed management interfaces are at higher risk and should be prioritized for patching. Additionally, operators should implement compensating controls such as network segmentation and access controls to limit the potential impact of a denial-of-service attack. Security teams should also review their incident response plans to ensure they are prepared to respond to potential denial-of-service attacks. This includes updating the

Technical summary

The Gallagher Command Centre Server is vulnerable to an Improper Locking issue (CWE-667) in the Morpho integration. This allows a privileged operator to cause a limited denial-of-service condition. The vulnerability affects multiple versions of the Command Centre Server, including 9.40 prior to vEL9.40.1976(MR1), 9.30 prior to vEL9.30.3382 (MR4), 9.20 prior to vEL9.20.3783 (MR6), 9.10 prior to vEL9.10.4647 (MR9), and all versions of 9.00 and prior. To address this vulnerability, operators should prioritize patching Gallagher Command Centre Server instances, especially those with internet-exposed management interfaces, to prevent potential limited denial-of-service attacks.

Defensive priority

Operators should prioritize patching Gallagher Command Centre Server instances, especially those with internet-exposed management interfaces, to prevent potential limited denial-of-service attacks.

Recommended defensive actions

• Inventory and assess Gallagher Command Centre Server instances for exposure and apply patches
• Implement compensating controls such as network segmentation and access controls
• Monitor Command Centre Server logs for suspicious activity
• Verify vendor-supplied patches and apply them
• Update incident response plans to include procedures for potential denial-of-service attacks

Evidence notes

The CVE-2026-20757 record indicates an Improper Locking vulnerability in Gallagher Morpho integration, allowing a privileged operator to cause a limited denial-of-service in the Command Centre Server. Affected versions include Command Centre Server 9.40 prior to vEL9.40.1976(MR1), 9.30 prior to vEL9.30.3382 (MR4), 9.20 prior to vEL9.20.3783 (MR6), 9.10 prior to vEL9.10.4647 (MR9), and all versions of 9.00 and prior.

Official resources