---
id: CVE-2026-98021
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: reject oversized tx_queue_len at netlink parse time

  rtnl_create_link() assigns IFLA_TXQLEN directly to dev->tx_queue_len
  without going through netif_change_tx_que…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: reject oversized tx_queue_len at netlink parse time

  rtnl_create_link() assigns IFLA_TXQLEN directly to dev->tx_queue_len
  without going through netif_change_tx_que…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 38f7b870d4a6a5d3ec21557e849620cb7d032965 <
    45ca9f59b6c7ea70e0a17054902b8a556913db34
  - >-
    Linux >= 38f7b870d4a6a5d3ec21557e849620cb7d032965 <
    2fd0880f0272ec022906a05587fd91416ebecc38
  - >-
    Linux >= 38f7b870d4a6a5d3ec21557e849620cb7d032965 <
    a638a2625aa83160a394abe8e8b2e524a80c771b
  - >-
    Linux >= 38f7b870d4a6a5d3ec21557e849620cb7d032965 <
    1aa9e143bf51405665a793d4cc925e1c4f0c5922
  - Linux 2.6.23
published: '2026-09-25'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T11:17:30.613'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-98021'
references:
  - url: 'https://git.kernel.org/stable/c/1aa9e143bf51405665a793d4cc925e1c4f0c5922'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2fd0880f0272ec022906a05587fd91416ebecc38'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/45ca9f59b6c7ea70e0a17054902b8a556913db34'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a638a2625aa83160a394abe8e8b2e524a80c771b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-25T11:06:38.855Z'
---

## Overview

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

net: reject oversized tx_queue_len at netlink parse time

rtnl_create_link() assigns IFLA_TXQLEN directly to dev->tx_queue_len
without going through netif_change_tx_queue_len(), so a device created
with "ip link add ... txqueuelen 500000" bypasses the S16_MAX cap and
still triggers the oversized ring allocations in pfifo_fast, tun and
tap. The veth peer nest (rtnl_nla_parse_ifinfomsg()) and the
RTM_NEWLINK-on-existing-device path reach the same sinks.

Enforce the cap in ifla_policy instead: IFLA_TXQLEN becomes
NLA_POLICY_FULL_RANGE(NLA_U32, &txqlen_range) with
txqlen_range = { .min = 0, .max = S16_MAX }. All netlink consumers
parse against this policy - rtnl_setlink(), rtnl_newlink() (create
and change), and the veth peer nest - so every netlink path is capped
at parse time and rejects the attribute with -ERANGE plus a proper
"integer out of range" extack message before any device state is
modified (the RTM_SETLINK half-application wart is gone with it).

Document the bound in the rt-link.yaml netlink spec.

Conditions to recreate the bug:
- CONFIG_NET_SCHED=y, CONFIG_VETH=y, CONFIG_USER_NS=y, CONFIG_NET_NS=y.
- Unprivileged user in a fresh user+net namespace (unshare -Urn):
  ip link add v0 txqueuelen 500000 type veth peer name v1
  -> on the fixed kernel this is rejected with -ERANGE ("integer out
  of range" extack) instead of installing an oversized tx_queue_len
  that later inflates pfifo_fast/tun/tap ring allocations.
- ip link set v0 txqueuelen 500000 is likewise rejected at parse time.

## Remediation

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