---
id: CVE-2025-38193
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net_sched: sch_sfq: reject invalid perturb period

  Gerrard Tai reported that SFQ perturb_period has no range check yet,
  and this can be used to trigger a race condition…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net_sched: sch_sfq: reject invalid perturb period

  Gerrard Tai reported that SFQ perturb_period has no range check yet,
  and this can be used to trigger a race condition…
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-190
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 2.6.13, < 5.4.297'
  - 'linux_kernel >= 5.5, < 5.10.240'
  - 'linux_kernel >= 5.11, < 5.15.186'
  - 'linux_kernel >= 5.16, < 6.1.142'
  - 'linux_kernel >= 6.2, < 6.6.95'
  - 'linux_kernel >= 6.7, < 6.12.35'
  - 'linux_kernel >= 6.13, < 6.15.4'
  - linux_kernel = 2.6.12
  - linux_kernel = 6.16
  - debian_linux = 11.0
patched:
  - linux_kernel 6.15.4
published: '2025-07-04'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T22:18:34.207'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-38193'
references:
  - url: 'https://git.kernel.org/stable/c/0357da9149eac621f39e235a135ebf155f01f7c3'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2254d038dab9c194fe6a4b1ce31034f42e91a6e5'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/590b2d7d0beadba2aa576708a05a05f0aae39295'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/7ca52541c05c832d32b112274f81a985101f9ba8'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/956b5aebb349449b38d920d444ca1392d43719d1'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b11a50544af691b787384089b68f740ae20a441b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e0936ff56be4e08ad5b60ec26971eae0c40af305'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f9b97d466e6026ccbdda30bb5b71965b67ccbc82'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
  - cve.org
epss: 0.00205
epssPercentile: 0.10529
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-15T21:48:23.009487Z'
ingestedAt: '2026-10-15T22:48:25.498Z'
---

## Overview

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

net_sched: sch_sfq: reject invalid perturb period

Gerrard Tai reported that SFQ perturb_period has no range check yet,
and this can be used to trigger a race condition fixed in a separate patch.

We want to make sure ctl->perturb_period * HZ will not overflow
and is positive.


tc qd add dev lo root sfq perturb -10   # negative value : error
Error: sch_sfq: invalid perturb period.

tc qd add dev lo root sfq perturb 1000000000 # too big : error
Error: sch_sfq: invalid perturb period.

tc qd add dev lo root sfq perturb 2000000 # acceptable value
tc -s -d qd sh dev lo
qdisc sfq 8005: root refcnt 2 limit 127p quantum 64Kb depth 127 flows 128 divisor 1024 perturb 2000000sec
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0

## Affected

- `linux_kernel >= 2.6.13, < 5.4.297`
- `linux_kernel >= 5.5, < 5.10.240`
- `linux_kernel >= 5.11, < 5.15.186`
- `linux_kernel >= 5.16, < 6.1.142`
- `linux_kernel >= 6.2, < 6.6.95`
- `linux_kernel >= 6.7, < 6.12.35`
- `linux_kernel >= 6.13, < 6.15.4`
- `linux_kernel = 2.6.12`
- `linux_kernel = 6.16`
- `debian_linux = 11.0`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.15.4`