SB20260720247 - Improper locking in Linux kernel handshake
Published: July 20, 2026
Security Bulletin ID
SB20260720247
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-2026-63980)
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 handling in the net/handshake subsystem when canceling a TLS handshake from softirq context while the same lock is held in process context on the same CPU. A local user can trigger a TLS handshake cancellation race to cause a denial of service.
The issue results in a deadlock.
Remediation
Install update from vendor's website.