---
id: CVE-2026-23274
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: xt_IDLETIMER: reject rev0 reuse of ALARM timer labels

  IDLETIMER revision 0 rules reuse existing timers by label and always call
  mod_timer() on timer->timer.…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: xt_IDLETIMER: reject rev0 reuse of ALARM timer labels

  IDLETIMER revision 0 rules reuse existing timers by label and always call
  mod_timer() on timer->timer.…
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'
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.7, < 5.10.253'
  - 'linux_kernel >= 5.11, < 5.15.203'
  - 'linux_kernel >= 5.16, < 6.1.167'
  - 'linux_kernel >= 6.2, < 6.6.130'
  - 'linux_kernel >= 6.7, < 6.12.78'
  - 'linux_kernel >= 6.13, < 6.18.19'
  - 'linux_kernel >= 6.19, < 6.19.9'
  - linux_kernel = 7.0
patched:
  - linux_kernel 6.19.9
published: '2026-03-20'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T02:18:46.010'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-23274'
references:
  - url: 'https://git.kernel.org/stable/c/144f88054ba0180467356f40895bd660b5dceeec'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/28c7cfaf0c0ab17cbd7754092116fd1af45271f9'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/329f0b9b48ee6ab59d1ab72fef55fe8c6463a6cf'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/32e937dc6e97f5ed3cdfe3fc0b2b19a05e23fa44'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/54080355999381fed4a26129579a5765bab87491'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/5e7ece24c5cb75a60402aad4d803c7898ea40aa9'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f228b9ae2a7e84d1153616d8e71c4236cb1f1309'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f5ef97c13165542480a6ffdbe6f09f40bbb7cbf1'
    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
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-784472.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23274.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-23274'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2449572'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-23274'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-23274'
  - url: >-
      https://lore.kernel.org/linux-cve-announce/2026032034-CVE-2026-23274-ba1d@gregkh/T
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
  - score-dispute
epss: 0.0018
epssPercentile: 0.07458
ingestedAt: '2026-09-08T15:33:26.993Z'
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T15:07:15.752483Z'
cwe:
  - CWE-908
scores:
  nvd: 7.8
  vendor: 5.5
  cna: 7.8
---

## Overview

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

netfilter: xt_IDLETIMER: reject rev0 reuse of ALARM timer labels

IDLETIMER revision 0 rules reuse existing timers by label and always call
mod_timer() on timer->timer.

If the label was created first by revision 1 with XT_IDLETIMER_ALARM,
the object uses alarm timer semantics and timer->timer is never initialized.
Reusing that object from revision 0 causes mod_timer() on an uninitialized
timer_list, triggering debugobjects warnings and possible panic when
panic_on_warn=1.

Fix this by rejecting revision 0 rule insertion when an existing timer with
the same label is of ALARM type.

## Affected

- `linux_kernel >= 5.7, < 5.10.253`
- `linux_kernel >= 5.11, < 5.15.203`
- `linux_kernel >= 5.16, < 6.1.167`
- `linux_kernel >= 6.2, < 6.6.130`
- `linux_kernel >= 6.7, < 6.12.78`
- `linux_kernel >= 6.13, < 6.18.19`
- `linux_kernel >= 6.19, < 6.19.9`
- `linux_kernel = 7.0`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.19.9`

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9 · updated 2026-10-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23274.json)