---
id: CVE-2026-63970
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  vsock/virtio: bind uarg before filling zerocopy skb

  virtio_transport_send_pkt_info() allocates or reuses the zerocopy uarg
  before entering the send loop, but virtio_tr…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  vsock/virtio: bind uarg before filling zerocopy skb

  virtio_transport_send_pkt_info() allocates or reuses the zerocopy uarg
  before entering the send loop, but virtio_tr…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-416
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 6.7, < 6.12.97'
  - 'linux_kernel >= 6.13, < 6.18.35'
  - 'linux_kernel >= 6.19, < 7.0.12'
  - linux_kernel = 7.1
patched:
  - linux_kernel 7.0.12
published: '2026-07-19'
updated: '2026-10-02'
sourceUpdated: '2026-10-02T19:38:05.180'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-63970'
references:
  - url: 'https://git.kernel.org/stable/c/1e584c304cfb94a759417130b1fc6d30b30c4cce'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/5d317573f1d48e76cce5fb6250452b6e4102e0fb'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/72194f65050958e4c8e069adb6c5d89ef81ca197'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b62e2b2b4a50953ca952f3cd3f77dd62dc50fd5d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00175
epssPercentile: 0.06348
ingestedAt: '2026-10-02T22:33:09.807Z'
---

## Overview

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

vsock/virtio: bind uarg before filling zerocopy skb

virtio_transport_send_pkt_info() allocates or reuses the zerocopy uarg
before entering the send loop, but virtio_transport_alloc_skb() still
fills the skb before it inherits that uarg. When fixed-buffer vectored
zerocopy hits MAX_SKB_FRAGS, io_sg_from_iter() may partially attach
managed frags and return -EMSGSIZE. The rollback path call kfree_skb()
to free an skb that carries SKBFL_MANAGED_FRAG_REFS but no uarg, so
skb_release_data() falls through to ordinary frag unref.

Pass the uarg into virtio_transport_alloc_skb() and bind it immediately
before virtio_transport_fill_skb(). This keeps control or no-payload skbs
untouched while ensuring success and rollback share one lifetime rule.

## Affected

- `linux_kernel >= 6.7, < 6.12.97`
- `linux_kernel >= 6.13, < 6.18.35`
- `linux_kernel >= 6.19, < 7.0.12`
- `linux_kernel = 7.1`

## Remediation

Upgrade past the affected range:

- `linux_kernel 7.0.12`