SB20260720244 - Improper locking in Linux kernel bridge
Published: July 20, 2026
Security Bulletin ID
SB20260720244
CSH Severity
Low
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Local access
Highest impact
Denial of service
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Improper locking (CVE-ID: CVE-2026-63989)
CWE-ID: CWE-667 - Improper Locking
CVSSv4: 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]
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to improper lock management in the bridge netlink configuration path when processing bridge port netlink attributes. A local user can send a specially crafted netlink message to cause a kernel BUG due to sleeping in atomic context.
The issue is triggered when changing certain bridge port flags that lead to a call to dev_set_promiscuity().
Remediation
Install update from vendor's website.