---
id: CVE-2025-37915
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net_sched: drr: Fix double list add in class with netem as child qdisc

  As described in Gerrard's report [1], there are use cases where a netem
  child qdisc will make th…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net_sched: drr: Fix double list add in class with netem as child qdisc

  As described in Gerrard's report [1], there are use cases where a netem
  child qdisc will make th…
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-415
  - CWE-367
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.0.1, < 5.4.294'
  - 'linux_kernel >= 5.5, < 5.10.238'
  - 'linux_kernel >= 5.11, < 5.15.182'
  - 'linux_kernel >= 5.16, < 6.1.138'
  - 'linux_kernel >= 6.2, < 6.6.90'
  - 'linux_kernel >= 6.7, < 6.12.28'
  - 'linux_kernel >= 6.13, < 6.14.6'
  - linux_kernel = 5.0
  - linux_kernel = 6.15
patched:
  - linux_kernel 6.14.6
published: '2025-05-20'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T22:18:21.020'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-37915'
references:
  - url: 'https://git.kernel.org/stable/c/26e75716b94d6ff9be5ea07d63675c4d189f30b4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2968632880f1792007eedd12eeedf7f6e2b7e9f3'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4b07ac06b0a712923255aaf2691637693fc7100d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4f0ecf50cdf76da95828578a92f130b653ac2fcf'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/5da3aad1a13e7edb8ff0778a444ccf49930313e9'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ab2248110738d4429668140ad22f530a9ee730e1'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/db205b92dfe0501e5b92fb7cf00971d0e44ba3eb'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f99a3fbf023e20b626be4b0f042463d598050c9a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-37915.json
  - url: 'https://access.redhat.com/security/cve/CVE-2025-37915'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2367527'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2025-37915'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2025-37915'
  - url: >-
      https://lore.kernel.org/linux-cve-announce/2025052000-CVE-2025-37915-83e3@gregkh/T
tags:
  - nvd
  - csaf
  - vex
  - red-hat
  - cve.org
epss: 0.00225
epssPercentile: 0.13142
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-15T21:45:59.473711Z'
scores:
  nvd: 7.8
  vendor: 6.3
  cna: 7.8
ingestedAt: '2026-10-15T22:48:25.483Z'
---

## Overview

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

net_sched: drr: Fix double list add in class with netem as child qdisc

As described in Gerrard's report [1], there are use cases where a netem
child qdisc will make the parent qdisc's enqueue callback reentrant.
In the case of drr, there won't be a UAF, but the code will add the same
classifier to the list twice, which will cause memory corruption.

In addition to checking for qlen being zero, this patch checks whether the
class was already added to the active_list (cl_is_active) before adding
to the list to cover for the reentrant case.

[1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/

## Affected

- `linux_kernel >= 5.0.1, < 5.4.294`
- `linux_kernel >= 5.5, < 5.10.238`
- `linux_kernel >= 5.11, < 5.15.182`
- `linux_kernel >= 5.16, < 6.1.138`
- `linux_kernel >= 6.2, < 6.6.90`
- `linux_kernel >= 6.7, < 6.12.28`
- `linux_kernel >= 6.13, < 6.14.6`
- `linux_kernel = 5.0`
- `linux_kernel = 6.15`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.14.6`

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8 · updated 2026-10-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-37915.json)