---
id: CVE-2026-31423
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net/sched: sch_hfsc: fix divide-by-zero in rtsc_min()

  m2sm() converts a u32 slope to a u64 scaled value
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net/sched: sch_hfsc: fix divide-by-zero in rtsc_min()

  m2sm() converts a u32 slope to a u64 scaled value.  For large inputs
  (e.g. m1=4000000000), the result can reach 2…
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-369
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 2.6.12.1, < 5.10.253'
  - 'linux_kernel >= 5.11, < 5.15.203'
  - 'linux_kernel >= 5.16, < 6.1.168'
  - 'linux_kernel >= 6.2, < 6.6.134'
  - 'linux_kernel >= 6.7, < 6.12.81'
  - 'linux_kernel >= 6.13, < 6.18.22'
  - 'linux_kernel >= 6.19, < 6.19.12'
  - linux_kernel = 2.6.12
  - linux_kernel = 7.0
patched:
  - linux_kernel 6.19.12
published: '2026-04-13'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T02:19:04.200'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-31423'
references:
  - url: 'https://git.kernel.org/stable/c/17c1b9807b8a67d676b6dcf749ee932ebaa7f568'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/25b6821884713a31e2b49fb67b0ebd765b33e0a9'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4576100b8cd03118267513cafacde164b498b322'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ab1ff5890c7354afc7be56502fcfbd61f3b7ae4f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ad8e8fec40290a8c8cf145c0deaadf76f80c5163'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b9e6431cbea8bb1fae8069ed099b4ee100499835'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c56f78614e7781aaceca9bd3cb2128bf7d45c3bd'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d0aefec1b1a1ba2c1d251028dc2c4e5b4ce1fea5'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-019113.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-082556.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-457936.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.0012
epssPercentile: 0.01836
ingestedAt: '2026-09-08T15:33:26.991Z'
---

## Overview

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

net/sched: sch_hfsc: fix divide-by-zero in rtsc_min()

m2sm() converts a u32 slope to a u64 scaled value.  For large inputs
(e.g. m1=4000000000), the result can reach 2^32.  rtsc_min() stores
the difference of two such u64 values in a u32 variable `dsm` and
uses it as a divisor.  When the difference is exactly 2^32 the
truncation yields zero, causing a divide-by-zero oops in the
concave-curve intersection path:

  Oops: divide error: 0000
  RIP: 0010:rtsc_min (net/sched/sch_hfsc.c:601)
  Call Trace:
   init_ed (net/sched/sch_hfsc.c:629)
   hfsc_enqueue (net/sched/sch_hfsc.c:1569)
   [...]

Widen `dsm` to u64 and replace do_div() with div64_u64() so the full
difference is preserved.

## Affected

- `linux_kernel >= 2.6.12.1, < 5.10.253`
- `linux_kernel >= 5.11, < 5.15.203`
- `linux_kernel >= 5.16, < 6.1.168`
- `linux_kernel >= 6.2, < 6.6.134`
- `linux_kernel >= 6.7, < 6.12.81`
- `linux_kernel >= 6.13, < 6.18.22`
- `linux_kernel >= 6.19, < 6.19.12`
- `linux_kernel = 2.6.12`
- `linux_kernel = 7.0`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.19.12`