Improper locking in Linux kernel - CVE-2026-63988
Published: July 20, 2026
Vulnerability identifier: #VU138660
CSH Severity: Low
CVSS v4.0: 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/E:U/U:Clear
CVE-ID: CVE-2026-63988
CWE-ID: CWE-667
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: Linux Foundation
Affected software:
Linux kernel
Linux kernel
Detailed vulnerability description
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to improper lock management in brport_store() in the bridge sysfs interface when handling sysfs attribute writes that change bridge port flags and invoke dev_set_promiscuity(). A local user can write crafted values to affected bridge port sysfs attributes to cause a kernel BUG from sleeping in atomic context.
The issue affects non-STP bridge port attributes, while the STP-related path_cost and priority attributes are handled separately.
How to mitigate CVE-2026-63988
Install security update from vendor's repository.