---
id: CVE-2026-74663
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net/sched: reject overly deep qdisc hierarchies

  Deep qdisc hierarchies can lead to excessive recursion in qdisc tree
  walkers and exhaust the kernel stack
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net/sched: reject overly deep qdisc hierarchies

  Deep qdisc hierarchies can lead to excessive recursion in qdisc tree
  walkers and exhaust the kernel stack. The existing…
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-770
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    08dc49df1527b09d9ea225a7265bbf6c237097bf
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    a627d36c2a94e18c8c105ae68008786dfd85592e
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    9f69bb9fdaa2fe64b68bb62fb84d405784bee540
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    8ca8cdb74939581339e1ae370193c0adb5a85336
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    2759acf08a3454866660edcd3ef4e64139f254a6
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    a4b14a4df29d36458a943f9b521ddd0f940363cc
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    e2d658c6427844cee5bc654b436ca68d680b6148
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    dedd34b0f2310e28c5f6d4875cfbf4b7ed821c01
  - Linux 2.6.12
published: '2026-08-22'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T20:17:50.400'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-74663'
references:
  - url: 'https://git.kernel.org/stable/c/08dc49df1527b09d9ea225a7265bbf6c237097bf'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2759acf08a3454866660edcd3ef4e64139f254a6'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/8ca8cdb74939581339e1ae370193c0adb5a85336'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9f69bb9fdaa2fe64b68bb62fb84d405784bee540'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a4b14a4df29d36458a943f9b521ddd0f940363cc'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a627d36c2a94e18c8c105ae68008786dfd85592e'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/dedd34b0f2310e28c5f6d4875cfbf4b7ed821c01'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e2d658c6427844cee5bc654b436ca68d680b6148'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74663.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-74663'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2521389'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-74663'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-74663'
  - url: >-
      https://lore.kernel.org/linux-cve-announce/2026082228-CVE-2026-74663-88a3@gregkh/T
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
  - score-dispute
epss: 0.00129
epssPercentile: 0.02546
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T19:14:09.885396Z'
scores:
  nvd: 7.8
  vendor: 5.5
ingestedAt: '2026-10-14T13:30:58.530Z'
---

## Overview

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

net/sched: reject overly deep qdisc hierarchies

Deep qdisc hierarchies can lead to excessive recursion in qdisc tree
walkers and exhaust the kernel stack. The existing loop check does not
cover the create-and-graft path, so a hierarchy can still be extended by
creating a new child qdisc below an already deep parent.

Store the hierarchy depth in struct Qdisc and update it when qdiscs are
grafted. Reject new child qdiscs once the parent is already at the maximum
allowed depth.

## 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 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, … · updated 2026-10-17 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74663.json)