CVE-2026-64206 Linux CVE debrief

Who should care

Linux kernel maintainers and users, Bluetooth L2CAP developers, and security teams monitoring Linux kernel vulnerabilities should be aware of this HIGH severity vulnerability. They should review and apply the official patch to prevent potential deadlocks in the Bluetooth L2CAP subsystem.

Technical summary

The Linux kernel Bluetooth L2CAP subsystem has a deadlock vulnerability. l2cap_conn_del() takes conn->lock and then calls cancel_work_sync() for pending_rx_work, while process_pending_rx() takes the same mutex, causing a potential deadlock. The issue was resolved by canceling pending_rx_work before taking conn->lock. This fix ensures that the pending_rx_work is cancelled before attempting to acquire the conn->lock, thus preventing the deadlock.

Defensive priority

High priority for Linux kernel maintainers and developers to apply the fix and review Bluetooth L2CAP implementation.

Recommended defensive actions

• Apply the official patch to the Linux kernel
• Review and update Bluetooth L2CAP implementation
• Monitor Linux kernel security advisories
• 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 CVE record was published on 2026-07-20T17:18:22.620Z and has been modified since then. The NVD entry is currently Received. The vulnerability was resolved by reordering locking and work cancellation in l2cap_conn_del(). The issue was found by static analysis tool and manually reviewed against the current tree. The grounded PoC kept the l2cap_conn_ready() -> queue_work(..., &conn->pending_rx_work) submit path, the l2cap_conn_del() -> cancel_work_sync(&conn->pending_rx_work) teardown path, and the process_pending_rx() -> mutex_lock(&conn->lock) worker edge.

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.