CVE-2026-63871
Received Received - Intake

Race Condition in Linux Kernel Bluetooth ISO Stack

Publication date: 2026-07-19

Last updated on: 2026-07-19

Assigner: kernel.org

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

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Meta Information

Published
2026-07-19
Last Modified
2026-07-19
Generated
2026-07-20
AI Q&A
2026-07-19
EPSS Evaluated
N/A
NVD
CVE-2026-63871
EUVD
EUVD-2026-45556

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability is a data-race issue in the Linux kernel's Bluetooth ISO (isochronous) implementation. It occurs when functions like iso_connect_bis() or iso_connect_cis() access socket fields (dst, src, src_type) without proper locking. These fields can be modified concurrently by other operations like connect() or setsockopt(), leading to race conditions detected by KCSAN.

Detection Guidance

This vulnerability is a data race in the Linux kernel's Bluetooth ISO implementation. Detection requires kernel tracing tools like KASAN or KCSAN to identify data races. Use commands like 'echo 1 > /sys/kernel/debug/kcsan/enable' to enable KCSAN, then monitor kernel logs for race reports during Bluetooth operations.

Impact Analysis

This vulnerability could cause undefined behavior in Bluetooth ISO connections, potentially leading to crashes, memory corruption, or security issues. Attackers on the same system might exploit this to manipulate Bluetooth connections or gain unauthorized access.

Compliance Impact

This vulnerability involves a data race in the Linux kernel's Bluetooth ISO implementation, which could lead to memory corruption or undefined behavior. While not directly tied to GDPR or HIPAA, such vulnerabilities may impact compliance by compromising data integrity or confidentiality if exploited to access sensitive information.

Mitigation Strategies

Apply the Linux kernel patch that fixes this issue. Update to a kernel version containing the fix for CVE-2026-63871. If immediate patching is not possible, disable Bluetooth ISO functionality by unloading the related kernel modules or restricting Bluetooth operations until the patch is applied.

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