CVE-2026-64537 Linux CVE debrief

Who should care

Linux kernel users and administrators should be aware of this vulnerability and take necessary actions to update and validate their configurations. This includes reviewing exp_interval settings and ensuring that they are within the valid range. Additionally, operators, platform administrators, and security teams should assess their exposure and prioritize remediation efforts based on their specific environments and risk profiles. Compensating controls, such as monitoring and asset inventory, should be implemented to prevent OOM conditions while remediation is scheduled and verified. Affected product deployments in managed environments require immediate attention, and owners should be assigned for follow-up. Official advisories or CVE records should be reviewed to validate affected scope, severity, and vendor guidance. Exceptions should be tracked, and remediated assets should be retested before closing the item, with evidence documented accordingly. This vulnerability requires immediate attention as it can cause a denial of service (OOM) condition, and its resolution is crucial for maintaining system stability and security posture. Therefore, it is essential to implement the recommended actions and verify their effectiveness to prevent potential attacks. The resolution of this vulnerability highlights the importance of robust configuration validation and change management processes in maintaining the security and reliability of Linux kernel-based systems. By prioritizing this vulnerability and taking proactive measures, organizations can minimize their exposure and ensure the continuity of their operations. Furthermore, Linux kernel users and administrators should consider implementing additional security measures, such as monitoring and detection, to enhance their overall security posture and reduce the risk of similar vulnerabilities in the future. The implementation of these measures will help to prevent potential attacks and ensure the security and stability of Linux kernel-based systems. Linux kernel users and administrators should also consider reviewing their current configurations and updating them to ensure that they are secure and compliant with best-p

Technical summary

The vulnerability was caused by an invalid CCM interval configuration in the Linux kernel. The issue was resolved by validating exp_interval at configuration time and rejecting starting CCM TX when exp_interval had not yet been configured. This change prevents a denial-of-service (OOM) condition by ensuring that the worker does not fire immediately in a tight loop. Linux kernel users should review their configurations to ensure they are within the valid range [BR_CFM_CCM_INTERVAL_3_3_MS, BR_CFM_CCM_INTERVAL_10_MIN].

Defensive priority

This vulnerability requires immediate attention as it can cause a denial of service (OOM) condition.

Recommended defensive actions

• Update the Linux kernel to the latest version
• Review and validate exp_interval configuration
• Implement compensating controls to prevent OOM conditions
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.

Evidence notes

The vulnerability was resolved by validating exp_interval at configuration time. The netlink policy was updated to constrain IFLA_BRIDGE_CFM_CC_CONFIG_EXP_INTERVAL to the valid range [BR_CFM_CCM_INTERVAL_3_3_MS, BR_CFM_CCM_INTERVAL_10_MIN]. Additionally, starting CCM TX in br_cfm_cc_ccm_tx() was rejected when exp_interval had not yet been configured (defaults to 0 from kzalloc).

Official resources