---
id: CVE-2026-23270
title: >-
  net/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared
  blocks
summary: >-
  In the Linux kernel, the following vulnerability has been resolved:


  net/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared
  blocks


  As Paolo said earlier [1]:


  "Since the blamed commit below, classify can return TC_ACT_…
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'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 172ba7d46c202e679f3ccb10264c67416aaeb1c4 <
    bc4e5bb529823a09f02dbe96169de679a9db26e0
  - >-
    Linux >= 0b5b831122fc3789fff75be433ba3e4dd7b779d4 <
    fb3c380a54e33d1fd272cc342faa906d787d7ef1
  - >-
    Linux >= 73f7da5fd124f2cda9161e2e46114915e6e82e97 <
    5a110ddcc99bda77a28598b3555fe009eaab3828
  - >-
    Linux >= 3f14b377d01d8357eba032b4cabc8c1149b458b6 <
    524ce8b4ea8f64900b6c52b6a28df74f6bc0801e
  - >-
    Linux >= 3f14b377d01d8357eba032b4cabc8c1149b458b6 <
    380ad8b7c65ea7aa10ef2258297079ed5ac1f5b6
  - >-
    Linux >= 3f14b377d01d8357eba032b4cabc8c1149b458b6 <
    9deda0fcda5c1f388c5e279541850b71a2ccfcf4
  - >-
    Linux >= 3f14b377d01d8357eba032b4cabc8c1149b458b6 <
    11cb63b0d1a0685e0831ae3c77223e002ef18189
  - Linux f5346df0591d10bc948761ca854b1fae6d2ef441
  - Linux >= 5.15.148 < 5.15.203
  - Linux >= 6.1.75 < 6.1.167
  - Linux >= 6.6.14 < 6.6.130
  - Linux >= 6.7.2 < 6.8
  - Linux 6.8
published: '2026-03-18'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T08:45:13.038Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-23270'
references:
  - url: 'https://git.kernel.org/stable/c/bc4e5bb529823a09f02dbe96169de679a9db26e0'
  - url: 'https://git.kernel.org/stable/c/fb3c380a54e33d1fd272cc342faa906d787d7ef1'
  - url: 'https://git.kernel.org/stable/c/5a110ddcc99bda77a28598b3555fe009eaab3828'
  - url: 'https://git.kernel.org/stable/c/524ce8b4ea8f64900b6c52b6a28df74f6bc0801e'
  - url: 'https://git.kernel.org/stable/c/380ad8b7c65ea7aa10ef2258297079ed5ac1f5b6'
  - url: 'https://git.kernel.org/stable/c/9deda0fcda5c1f388c5e279541850b71a2ccfcf4'
  - url: 'https://git.kernel.org/stable/c/11cb63b0d1a0685e0831ae3c77223e002ef18189'
tags:
  - cve.org
epss: 0.00125
epssPercentile: 0.01888
ingestedAt: '2026-09-08T15:33:26.993Z'
---

## Overview

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

net/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared blocks

As Paolo said earlier [1]:

"Since the blamed commit below, classify can return TC_ACT_CONSUMED while
the current skb being held by the defragmentation engine. As reported by
GangMin Kim, if such packet is that may cause a UaF when the defrag engine
later on tries to tuch again such packet."

act_ct was never meant to be used in the egress path, however some users
are attaching it to egress today [2]. Attempting to reach a middle
ground, we noticed that, while most qdiscs are not handling
TC_ACT_CONSUMED, clsact/ingress qdiscs are. With that in mind, we
address the issue by only allowing act_ct to bind to clsact/ingress
qdiscs and shared blocks. That way it's still possible to attach act_ct to
egress (albeit only with clsact).

[1] https://lore.kernel.org/netdev/674b8cbfc385c6f37fb29a1de08d8fe5c2b0fbee.1771321118.git.pabeni@redhat.com/
[2] https://lore.kernel.org/netdev/cc6bfb4a-4a2b-42d8-b9ce-7ef6644fb22b@ovn.org/

## Affected

- `Linux >= 172ba7d46c202e679f3ccb10264c67416aaeb1c4 < bc4e5bb529823a09f02dbe96169de679a9db26e0`
- `Linux >= 0b5b831122fc3789fff75be433ba3e4dd7b779d4 < fb3c380a54e33d1fd272cc342faa906d787d7ef1`
- `Linux >= 73f7da5fd124f2cda9161e2e46114915e6e82e97 < 5a110ddcc99bda77a28598b3555fe009eaab3828`
- `Linux >= 3f14b377d01d8357eba032b4cabc8c1149b458b6 < 524ce8b4ea8f64900b6c52b6a28df74f6bc0801e`
- `Linux >= 3f14b377d01d8357eba032b4cabc8c1149b458b6 < 380ad8b7c65ea7aa10ef2258297079ed5ac1f5b6`
- `Linux >= 3f14b377d01d8357eba032b4cabc8c1149b458b6 < 9deda0fcda5c1f388c5e279541850b71a2ccfcf4`
- `Linux >= 3f14b377d01d8357eba032b4cabc8c1149b458b6 < 11cb63b0d1a0685e0831ae3c77223e002ef18189`
- `Linux f5346df0591d10bc948761ca854b1fae6d2ef441`
- `Linux >= 5.15.148 < 5.15.203`
- `Linux >= 6.1.75 < 6.1.167`
- `Linux >= 6.6.14 < 6.6.130`
- `Linux >= 6.7.2 < 6.8`
- `Linux 6.8`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.