---
id: CVE-2026-98009
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net/sched: ets: clamp quantum in parse and fallback paths

  ets_qdisc_change() falls back to psched_mtu() with no floor for bands
  without an explicit quantum
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net/sched: ets: clamp quantum in parse and fallback paths

  ets_qdisc_change() falls back to psched_mtu() with no floor for bands
  without an explicit quantum. With a cra…
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-835
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= dcc68b4d8084e1ac9af0d4022d6b1aff6a139a33 <
    440b66cc7b56ea38e9b878ae88da91992efaa4c4
  - >-
    Linux >= dcc68b4d8084e1ac9af0d4022d6b1aff6a139a33 <
    4ef8664eafafc8db68a1d52601f17dc008a223b7
  - >-
    Linux >= dcc68b4d8084e1ac9af0d4022d6b1aff6a139a33 <
    8b8d782c3b96376217087767dcf662cd3d25f226
  - >-
    Linux >= dcc68b4d8084e1ac9af0d4022d6b1aff6a139a33 <
    226d2702e74a570f5bfae6115b4706da4b94e5cf
  - >-
    Linux >= dcc68b4d8084e1ac9af0d4022d6b1aff6a139a33 <
    99ae477b892e203a37985ebc56f0063e072f7f4b
  - >-
    Linux >= dcc68b4d8084e1ac9af0d4022d6b1aff6a139a33 <
    8f80b113dea0bed3c1a31a4224b72775cd9ec52d
  - >-
    Linux >= dcc68b4d8084e1ac9af0d4022d6b1aff6a139a33 <
    de22c30ec5598aca8797f02082d2ee1358dfa3ff
  - >-
    Linux >= dcc68b4d8084e1ac9af0d4022d6b1aff6a139a33 <
    1c38487f46b243bfeefec0c0c86023a3904f2214
  - Linux 5.6
published: '2026-09-25'
updated: '2026-10-03'
sourceUpdated: '2026-10-03T11:18:23.873'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-98009'
references:
  - url: 'https://git.kernel.org/stable/c/1c38487f46b243bfeefec0c0c86023a3904f2214'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/226d2702e74a570f5bfae6115b4706da4b94e5cf'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/440b66cc7b56ea38e9b878ae88da91992efaa4c4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4ef8664eafafc8db68a1d52601f17dc008a223b7'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/8b8d782c3b96376217087767dcf662cd3d25f226'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/8f80b113dea0bed3c1a31a4224b72775cd9ec52d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/99ae477b892e203a37985ebc56f0063e072f7f4b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/de22c30ec5598aca8797f02082d2ee1358dfa3ff'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98009.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-98009'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2541140'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-98009'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-98009'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98009.mbox
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00177
epssPercentile: 0.07163
cvssSource: vendor
ingestedAt: '2026-09-25T11:06:38.859Z'
---

## Overview

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

net/sched: ets: clamp quantum in parse and fallback paths

ets_qdisc_change() falls back to psched_mtu() with no floor for bands
without an explicit quantum. With a crafted size table qdisc_pkt_len
reaches ~2 GiB, so a zero psched_mtu on a headerless device makes the
deficit-refill loop spin under the qdisc lock.

Move the floor into ets_quantum_parse() so explicitly configured quanta
are also clamped to [256, 1<<20], not just the fallback path.

Conditions to recreate the bug:
  CONFIG_NET_SCH_ETS=y. Requires CAP_NET_ADMIN (namespace-local via
  unshare -Urn suffices).

  tc qdisc add dev dummy0 root ets bands 3 strict 2 quanta 1 1

## Remediation

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

## Vendor advisories

- **Red Hat VEX** · Low · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-10-17 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98009.json)