---
id: CVE-2026-80742
title: 'af_packet: Don''t send zero-byte data in tpacket_snd().'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  af_packet: Don't send zero-byte data in tpacket_snd().

  syzbot reported a WARNING in __dev_queue_xmit() triggered via tpacket_snd():

  skb_assert_len
  WARNING: at include…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    dde212f8622f5cb36223fff1ebd6e6f2a3dc61fe
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    80a702964467b998d254f16cc61c2c9a20540c9d
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    7521e691c7c4f2231634c95053281ac888d1f452
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    1fc70b3d513bafb16b17540178870ef46e81c0bb
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    3fa110f9e2ea96f567f2194c673c4bc327640111
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    98c5914d6b7bd4b4675535908e57dea31f1efd6a
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    f09ac5682f1bb67981fcb6ead4d3cfe439225876
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    6bcd76c134c55c697148acb5c0194e9666abdf84
  - Linux 2.6.12
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-06T17:02:59.452949Z'
published: '2026-09-03'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T17:05:53.513Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-80742'
references:
  - url: 'https://git.kernel.org/stable/c/dde212f8622f5cb36223fff1ebd6e6f2a3dc61fe'
  - url: 'https://git.kernel.org/stable/c/80a702964467b998d254f16cc61c2c9a20540c9d'
  - url: 'https://git.kernel.org/stable/c/7521e691c7c4f2231634c95053281ac888d1f452'
  - url: 'https://git.kernel.org/stable/c/1fc70b3d513bafb16b17540178870ef46e81c0bb'
  - url: 'https://git.kernel.org/stable/c/3fa110f9e2ea96f567f2194c673c4bc327640111'
  - url: 'https://git.kernel.org/stable/c/98c5914d6b7bd4b4675535908e57dea31f1efd6a'
  - url: 'https://git.kernel.org/stable/c/f09ac5682f1bb67981fcb6ead4d3cfe439225876'
  - url: 'https://git.kernel.org/stable/c/6bcd76c134c55c697148acb5c0194e9666abdf84'
tags:
  - cve.org
epss: 0.00177
epssPercentile: 0.0727
ingestedAt: '2026-11-06T18:00:12.534Z'
---

## Overview

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

af_packet: Don't send zero-byte data in tpacket_snd().

syzbot reported a WARNING in __dev_queue_xmit() triggered via tpacket_snd():

skb_assert_len
WARNING: at include/linux/skbuff.h:2753 skb_assert_len
WARNING: at __dev_queue_xmit+0x21bc/0x4970 net/core/dev.c:4781

Call Trace:
 <TASK>
 dev_queue_xmit include/linux/netdevice.h:3448 [inline]
 packet_xmit+0x243/0x310 net/packet/af_packet.c:276
 tpacket_snd net/packet/af_packet.c:2907 [inline]
 packet_sendmsg+0x28d6/0x4eb0 net/packet/af_packet.c:3134

When sending 0-byte packets via TPACKET ring buffer on devices with no
hard header (e.g. dev->hard_header_len == 0), tpacket_fill_skb()
populates an skb with skb->len == 0 and returns 0. tpacket_snd() then
forwards this empty skb to packet_xmit(), causing __dev_queue_xmit() to
hit skb_assert_len(skb).

Similar checks exist in packet_snd() via commit dc633700f00f
("net/af_packet: check len when min_header_len equals to 0") and in
packet_sendmsg_spkt() via commit 6a341729fb31 ("af_packet: Don't send
zero-byte data in packet_sendmsg_spkt().").

Return -EINVAL in tpacket_fill_skb() when skb->len is zero to reject
zero-length packets in tpacket_snd().

## Affected

- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < dde212f8622f5cb36223fff1ebd6e6f2a3dc61fe`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 80a702964467b998d254f16cc61c2c9a20540c9d`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 7521e691c7c4f2231634c95053281ac888d1f452`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 1fc70b3d513bafb16b17540178870ef46e81c0bb`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 3fa110f9e2ea96f567f2194c673c4bc327640111`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 98c5914d6b7bd4b4675535908e57dea31f1efd6a`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < f09ac5682f1bb67981fcb6ead4d3cfe439225876`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 6bcd76c134c55c697148acb5c0194e9666abdf84`
- `Linux 2.6.12`

## Remediation

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