---
id: CVE-2026-74684
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: tap: set skb->dev before parsing virtio net header in tap_get_user_xdp()

  The commit 4f61f133f354 ("net: tap: NULL pointer derefence in
  dev_parse_header_protocol w…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: tap: set skb->dev before parsing virtio net header in tap_get_user_xdp()

  The commit 4f61f133f354 ("net: tap: NULL pointer derefence in
  dev_parse_header_protocol w…
severity: high
cvss: 7.1
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H'
published: '2026-08-22'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T13:10:00.187'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-74684'
references:
  - url: 'https://git.kernel.org/stable/c/15583b07fd691a844fbf7b3ad612cdc9e9a657c0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/164c31ee252ebd1ac8f44c2dfc5486b6d9a0379b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/3874892dd27d5387aa9a06f58d9060f18f351d24'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/8b444b126cd8e4473e652f529753ed4dd1360a9c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00146
epssPercentile: 0.03377
ingestedAt: '2026-10-14T13:30:58.536Z'
---

## Overview

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

net: tap: set skb->dev before parsing virtio net header in tap_get_user_xdp()

The commit 4f61f133f354 ("net: tap: NULL pointer derefence in
dev_parse_header_protocol when skb->dev is null") fixed a crash in
tap_get_user() by assigning skb->dev before calling tun_vnet_hdr_to_skb().
This is required because virtio_net_hdr_to_skb() may invoke
dev_parse_header_protocol(), which dereferences skb->dev. Without the
assignment, a NULL pointer dereference can occur.

However, tap_get_user_xdp() still parses the virtio-net header before
assigning skb->dev. When the vhost TX path passes an XDP buffer containing
a GSO virtio-net header but the protocol is set to zero on purpose,
tun_vnet_hdr_to_skb() can reach dev_parse_header_protocol() while skb->dev
is still NULL, resulting in a crash.

Fix this by looking up the tap device and assigning skb->dev before calling
tun_vnet_hdr_to_skb(), matching the ordering already used in
tap_get_user(). Preserve the existing RCU read-side critical section across
dev_queue_xmit().

## Remediation

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