Improper locking in Linux kernel - CVE-2026-63980
Published: July 20, 2026
Vulnerability identifier: #VU138664
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-2026-63980
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 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.
How to mitigate CVE-2026-63980
Install security update from vendor's repository.