Race condition in Linux kernel - CVE-2026-63871

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Main Vulnerability Database Vulnerabilities #VU138780

Race condition in Linux kernel - CVE-2026-63871

Published: July 20, 2026


Vulnerability identifier: #VU138780
CSH Severity: Low
CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-63871
CWE-ID: CWE-362
Exploitation vector: Local access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to a race condition in Bluetooth ISO socket handling in net/bluetooth/iso.c when calling hci_get_route() on iso_pi socket fields without holding the socket lock. A local user can trigger concurrent connect() or setsockopt() operations on the same socket to cause a denial of service.

The issue was reported by KCSAN as a data race during Bluetooth ISO connection and listening operations.


Affected software

Linux kernel
Ubuntu
linux (Ubuntu package)
linux-lowlatency (Ubuntu package)
linux-raspi (Ubuntu package)
linux-gcp (Ubuntu package)
linux-azure (Ubuntu package)
linux-aws (Ubuntu package)
linux-ibm (Ubuntu package)
linux-oracle (Ubuntu package)
linux-azure-fde (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-realtime (Ubuntu package)
linux-hwe-6.8 (Ubuntu package)
linux-lowlatency-hwe-6.8 (Ubuntu package)
linux-fips (Ubuntu package)
linux-azure-fde-6.8 (Ubuntu package)
linux-aws-6.8 (Ubuntu package)
linux-azure-6.8 (Ubuntu package)
linux-oracle-6.8 (Ubuntu package)
linux-nvidia-tegra (Ubuntu package)
linux-nvidia-lowlatency (Ubuntu package)
linux-gkeop (Ubuntu package)
linux-nvidia-6.8 (Ubuntu package)
linux-gke (Ubuntu package)
linux-ibm-6.8 (Ubuntu package)
linux-gcp-6.8 (Ubuntu package)
linux-aws-fips (Ubuntu package)
linux-gcp-fips (Ubuntu package)
linux-azure-fips (Ubuntu package)
linux-raspi-realtime (Ubuntu package)
linux-realtime-6.8 (Ubuntu package)
linux-nvidia-bos (Ubuntu package)
linux-hwe-7.0 (Ubuntu package)
linux-oracle-7.0 (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux-azure-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
linux-aws-7.0 (Ubuntu package)
linux-nvidia-7.0 (Ubuntu package)

How to mitigate CVE-2026-63871

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - addressed in versions 6.8.0-146.146, 7.0.0-31.31
linux-lowlatency (Ubuntu package) - update to 6.8.0-146.146.1
linux-raspi (Ubuntu package) - addressed in versions 6.8.0-1068.72, 7.0.0-1019.19
linux-gcp (Ubuntu package) - addressed in versions 6.8.0-1070.78, 7.0.0-1011.11
linux-azure (Ubuntu package) - addressed in versions 6.8.0-1070.78, 7.0.0-1014.14
linux-aws (Ubuntu package) - addressed in versions 6.8.0-1066.69, 7.0.0-1012.12
linux-ibm (Ubuntu package) - addressed in versions 6.8.0-1066.67, 7.0.0-1013.13
linux-oracle (Ubuntu package) - addressed in versions 6.8.0-1063.66, 7.0.0-1011.11
linux-azure-fde (Ubuntu package) - update to 6.8.0-1068.75
linux-nvidia (Ubuntu package) - addressed in versions 6.8.0-1064.67, 7.0.0-1018.18
linux-realtime (Ubuntu package) - addressed in versions 6.8.1-1061.62, 7.0.0-31.31.1
linux-hwe-6.8 (Ubuntu package) - update to 6.8.0-149.149~22.04.1
linux-lowlatency-hwe-6.8 (Ubuntu package) - update to 6.8.0-146.146.1~22.04.1
linux-fips (Ubuntu package) - update to 6.8.0-146.146+fips1
linux-azure-fde-6.8 (Ubuntu package) - update to 6.8.0-1068.75~22.04.1
linux-aws-6.8 (Ubuntu package) - update to 6.8.0-1066.69~22.04.1
linux-azure-6.8 (Ubuntu package) - update to 6.8.0-1070.78~22.04.1
linux-oracle-6.8 (Ubuntu package) - update to 6.8.0-1067.71~22.04.1
linux-nvidia-tegra (Ubuntu package) - update to 6.8.0-1038.42
linux-nvidia-lowlatency (Ubuntu package) - update to 6.8.0-1064.67.1
linux-gkeop (Ubuntu package) - update to 6.8.0-1051.55
linux-nvidia-6.8 (Ubuntu package) - update to 6.8.0-1064.67~22.04.1
linux-gke (Ubuntu package) - addressed in versions 6.8.0-1065.73, 7.0.0-1006.7
linux-ibm-6.8 (Ubuntu package) - update to 6.8.0-1066.67~22.04.1
linux-gcp-6.8 (Ubuntu package) - update to 6.8.0-1070.78~22.04.1
linux-aws-fips (Ubuntu package) - update to 6.8.0-1066.69+fips1
linux-gcp-fips (Ubuntu package) - update to 6.8.0-1070.78+fips1
linux-azure-fips (Ubuntu package) - update to 6.8.0-1069.77+fips1
linux-raspi-realtime (Ubuntu package) - update to 6.8.0-2056.58
linux-realtime-6.8 (Ubuntu package) - update to 6.8.1-1061.62~22.04.1
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2018.18
linux-hwe-7.0 (Ubuntu package) - update to 7.0.0-31.31~24.04.1
linux-oracle-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-gcp-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-azure-7.0 (Ubuntu package) - update to 7.0.0-1014.14~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1013.13
linux-aws-7.0 (Ubuntu package) - update to 7.0.0-1012.12~24.04.1
linux-nvidia-7.0 (Ubuntu package) - update to 7.0.0-1018.18~24.04.1

External References

Related Security Bulletins