CVE-2026-98737 Linux CVE debrief

Who should care

Linux kernel developers and maintainers, Bluetooth HCI sync command worker users, Linux distribution maintainers, system administrators, security teams, and users of Linux-based systems that utilize Bluetooth HCI sync command workers should review and apply patches to prevent use-after-free conditions. They should also monitor Linux kernel security advisories for related updates and review Bluetooth HCI sync command worker usage and configurations.

Why it matters

A use-after-free vulnerability in the Linux kernel's Bluetooth HCI sync command worker can lead to a crash or potentially allow an attacker to execute arbitrary code. Linux kernel developers and maintainers should review and apply patches to prevent use-after-free conditions.

• Verify Linux kernel versions and apply patches to prevent use-after-free conditions
• Monitor Linux kernel security advisories for related updates
• Review Bluetooth HCI sync command worker usage and configurations

Technical summary

The vulnerability occurs in the Linux kernel's Bluetooth HCI sync command worker. The worker holds hdev->req_lock, but inquiry-cache updates and flushes use hdev->lock. This can lead to a use-after-free condition when a concurrent HCIINQUIRY ioctl acquires hdev->lock and flushes the cache, freeing the entry. The issue arises from the race condition between the worker's lock and the inquiry-cache updates. To address this, developers should review and apply patches to prevent use-after-free conditions. The vulnerability was reported by KASAN and can lead to a crash or potentially allow an attacker to execute arbitrary code.

Defensive priority

Medium

Recommended defensive actions

• Review and apply the provided patches to the Linux kernel
• Ensure that the Linux kernel is updated to a version that includes the fix
• Monitor the Linux kernel for any related security advisories or updates
• Verify Linux kernel versions and apply patches to prevent use-after-free conditions
• Review Bluetooth HCI sync command worker usage and configurations
• 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

Evidence notes

The vulnerability was reported by KASAN and occurs in the Linux kernel's Bluetooth HCI sync command worker. The use-after-free condition can lead to a crash or potentially allow an attacker to execute arbitrary code.

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.