---
id: CVE-2026-64523
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net/handshake: Take a long-lived file reference at submit

  handshake_nl_accept_doit() needs the file pointer backing
  req->hr_sk->sk_socket to survive the window between…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net/handshake: Take a long-lived file reference at submit

  handshake_nl_accept_doit() needs the file pointer backing
  req->hr_sk->sk_socket to survive the window between…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
published: '2026-07-25'
updated: '2026-08-09'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-64523'
references:
  - url: 'https://git.kernel.org/stable/c/09dba37eee70d0596e26645015f1aa95a9848e9d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/16eaba5aa89c04eea125905bb8f988c1897f4f29'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/685b10dd0e32c7782cead16c8cf055c609678583'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b913801ad9b9a51437d84d030ec6843e08976bd6'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00671
epssPercentile: 0.49871
ingestedAt: '2026-08-09T19:34:41.265Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

net/handshake: Take a long-lived file reference at submit

handshake_nl_accept_doit() needs the file pointer backing
req->hr_sk->sk_socket to survive the window between
handshake_req_next() and the subsequent FD_PREPARE() and get_file().
The submit-side sock_hold() does not provide that.  sk_refcnt keeps
struct sock alive, but struct socket is owned by sock->file: when
the consumer fputs the last file reference, sock_release() tears
the socket down regardless of any sock_hold.

Add an hr_file pointer to struct handshake_req and acquire an
explicit reference on sock->file during handshake_req_submit().
handshake_complete() and handshake_req_cancel() release the
reference on the completion-bit-winning path.

The submit error path must also release the file reference, but
after rhashtable insertion a concurrent handshake_req_cancel() can
discover the request and race the error path.  Gate the error-path
cleanup -- sk_destruct restoration, fput, and request destruction
-- with test_and_set_bit(HANDSHAKE_F_REQ_COMPLETED), the same
serialization handshake_complete() and handshake_req_cancel()
already use.  When cancel has already claimed ownership, the submit
error path returns without touching the request; socket teardown
handles final destruction.

The accept-side dereferences are not yet retargeted; that change
comes in the next patch.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.