CVE-2026-98736 Linux CVE debrief

Who should care

Linux kernel developers and maintainers, Bluetooth subsystem developers, and users of Linux-based systems that use Bluetooth. These individuals should review and apply the patch to the Linux kernel, ensure that the Linux kernel is updated to the latest version, and monitor Bluetooth connections for suspicious activity.

Why it matters

A use-after-free vulnerability in the Linux kernel's Bluetooth subsystem requires patching and updating to prevent potential code execution or denial of service.

• Potential code execution or denial of service
• Increased risk of system compromise
• Need for patching and updating Linux kernel

Technical summary

The `hci_enhanced_setup_sync` function in the Linux kernel's Bluetooth subsystem is vulnerable to a use-after-free condition. The function is called without holding the `hci_dev_lock`, which can lead to a use-after-free condition when accessing the `conn->parent` pointer. This vulnerability can be exploited by an attacker to execute arbitrary code or cause a denial of service. The vulnerability was fixed by holding the `hci_dev_lock` across the codec switch. The affected product context is the Linux kernel's Bluetooth subsystem.

Defensive priority

High

Recommended defensive actions

• Review and apply the patch to the Linux kernel
• Ensure that the Linux kernel is updated to the latest version
• Monitor Bluetooth connections for suspicious activity
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The vulnerability was discovered in the Linux kernel's Bluetooth subsystem. The `hci_enhanced_setup_sync` function is called without holding the `hci_dev_lock`, which can lead to a use-after-free condition. The vulnerability was fixed by holding the `hci_dev_lock` across the codec switch. The evidence limits are based on the CVE record and the NVD detail page. Defenders should verify that the Linux kernel is updated to the latest version and that Bluetooth connections are monitored for suspicious activity.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.