CVE-2026-63871 Bluetooth: ISO: Fix data-race on iso_pi fields in hci_get_route calls
A data race in the Linux kernel Bluetooth ISO subsystem allows local attackers to trigger a kernel crash via concurrent socket operations.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-63871?
CVE-2026-63871 is a vulnerability in Linux, published on 19 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: ISO: Fix data-race on iso_pi fields in hci_get_route calls
iso_connect_bis(), iso_connect_cis(), iso_listen_bis(), and iso_conn_big_sync() call hci_get_route() using iso_pi(sk)->dst, iso_pi(sk)->src, and iso_pi(sk)->src_type without holding lock_sock().
These fields may be modified concurrently by connect() or setsockopt() on the same socket, resulting in data-races reported by KCSAN.
Fix this by snapshotting the required fields under lock_sock() before calling hci_get_route().
BUG: KCSAN: data-race in memcmp+0x45/0xb0
race at unknown origin, with read to 0xffff8880122135cf of 1 bytes by task 333 on cpu 1: memcmp+0x45/0xb0 hci_get_route+0x27e/0x490 iso_connect_cis+0x4c/0xa10 iso_sock_connect+0x60e/0xb30 __sys_connect_file+0xbd/0xe0 __sys_connect+0xe0/0x110 __x64_sys_connect+0x40/0x50 x64_sys_call+0xcad/0x1c60 do_syscall_64+0x133/0x590 entry_SYSCALL_64_after_hwframe+0x77/0x7f
Which versions are affected by CVE-2026-63871?
How do I fix CVE-2026-63871?
Apply the vendor's patch.
Is CVE-2026-63871 being exploited?
There is no known exploitation of CVE-2026-63871 in the wild and no public exploit code.
Sources
Also known as AZL-92570, BELL-CVE-2026-63871, DEBIAN-CVE-2026-63871, GHSA-5243-p4qj-j66v, ROOT-OS-DEBIAN-12-CVE-2026-63871, UBUNTU-CVE-2026-63871.