---
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'
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-2026-74663'
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
tags:
  - nvd
epss: 0.00129
epssPercentile: 0.02245
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.