CVE-2026-63946 Linux CVE debrief

Who should care

Linux kernel maintainers, Linux distribution vendors, and organizations using Linux-based systems should be aware of this vulnerability and take steps to ensure their systems are updated with the patched kernel.

Technical summary

The Linux kernel's Bluetooth ISO module has a use-after-free vulnerability in the iso_recv_frame function. The function reads the conn->sk pointer under the iso_conn_lock but releases the lock before using the sk pointer, with no reference held. This can cause a concurrent iso_sock_kill() to free the sk pointer in that window, leading to a use-after-free issue on sk->sk_state and sock_queue_rcv_skb(). The fix involves replacing the bare pointer read with iso_sock_hold(conn), which calls sock_hold() while the spinlock is held, atomically elevating the refcount before the lock drops.

Defensive priority

High

Recommended defensive actions

• Update Linux kernel to the latest version with the patched Bluetooth ISO module
• Verify Linux kernel configurations and modules for secure settings
• Monitor Linux system logs for potential exploitation attempts
• Implement additional security controls, such as network segmentation and access controls
• Perform vulnerability scanning to identify potentially affected systems
• Review system change management processes to ensure timely patching
• Isolate affected systems from critical networks until patched

Evidence notes

The CVE record was published on 2026-07-19T16:17:13.223Z and has not been modified since then. The NVD entry is currently Received. The Linux kernel's Bluetooth ISO module has a use-after-free vulnerability in the iso_recv_frame function. Evidence is limited to public CVE and NVD data. Defenders should verify Linux kernel configurations and modules for secure settings.

Official resources