Use-after-free in Linux kernel - CVE-2026-63979
Published: July 20, 2026
Vulnerability identifier: #VU138663
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-2026-63979
CWE-ID: CWE-416
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 a use-after-free in the net/handshake accept-side request handling code when processing queued handshake requests during concurrent cancellation. A local user can trigger a race condition to cause a denial of service.
The issue occurs because the accept side dereferences req->hr_sk->sk_socket->file after the request is removed from the pending list, while a concurrent cancellation path can release sock->file, clear sk_socket, or free the associated struct socket.
How to mitigate CVE-2026-63979
Install security update from vendor's repository.