---
id: CVE-2026-89488
title: 'openvswitch: Fix CT limit teardown use-after-free'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  openvswitch: Fix CT limit teardown use-after-free

  Packet processing uses CT limit state under RCU, while netns teardown
  frees that state under ovs_mutex. The CT limit …
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
cwe:
  - CWE-825
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 11efd5cb04a184eea4f57b68ea63dddd463158d1 <
    239f26589a6926db28c436e14f28517581ef1385
  - >-
    Linux >= 11efd5cb04a184eea4f57b68ea63dddd463158d1 <
    3b9369881b403f4cdbb11fa998554382bdcc3d8c
  - >-
    Linux >= 11efd5cb04a184eea4f57b68ea63dddd463158d1 <
    3b41d907400cc1dd1da9555b81dca422b1f44433
  - >-
    Linux >= 11efd5cb04a184eea4f57b68ea63dddd463158d1 <
    680f20d5937fa4d1367c59fe83091b78041015f5
  - >-
    Linux >= 11efd5cb04a184eea4f57b68ea63dddd463158d1 <
    bf4aaa7ea2579e24ed7de2e20578a875bebca011
  - >-
    Linux >= 11efd5cb04a184eea4f57b68ea63dddd463158d1 <
    e15407c3a8a005324f633cd46cd8fb58042c1157
  - >-
    Linux >= 11efd5cb04a184eea4f57b68ea63dddd463158d1 <
    6a6d36fadb8537d9b79e72c9fa51885ec0c33e10
  - >-
    Linux >= 11efd5cb04a184eea4f57b68ea63dddd463158d1 <
    403f96c32c9e24600093d7d0c61c17daeedca957
  - Linux 4.18
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T19:22:48.434691Z'
published: '2026-09-11'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T08:47:38.827Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-89488'
references:
  - url: 'https://git.kernel.org/stable/c/239f26589a6926db28c436e14f28517581ef1385'
  - url: 'https://git.kernel.org/stable/c/3b9369881b403f4cdbb11fa998554382bdcc3d8c'
  - url: 'https://git.kernel.org/stable/c/3b41d907400cc1dd1da9555b81dca422b1f44433'
  - url: 'https://git.kernel.org/stable/c/680f20d5937fa4d1367c59fe83091b78041015f5'
  - url: 'https://git.kernel.org/stable/c/bf4aaa7ea2579e24ed7de2e20578a875bebca011'
  - url: 'https://git.kernel.org/stable/c/e15407c3a8a005324f633cd46cd8fb58042c1157'
  - url: 'https://git.kernel.org/stable/c/6a6d36fadb8537d9b79e72c9fa51885ec0c33e10'
  - url: 'https://git.kernel.org/stable/c/403f96c32c9e24600093d7d0c61c17daeedca957'
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89488.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89488'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532407'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89488'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89488'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89488.mbox
tags:
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00126
epssPercentile: 0.02234
scores:
  cna: 7.8
  vendor: 7
ingestedAt: '2026-09-14T15:23:07.452Z'
---

## Overview

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

openvswitch: Fix CT limit teardown use-after-free

Packet processing uses CT limit state under RCU, while netns teardown
frees that state under ovs_mutex. The CT limit pointer was neither removed
from readers nor protected by a grace period, allowing packet processing to
dereference the freed state.

An unprivileged user can trigger this bug from a user and network
namespace, causing a slab-use-after-free in ovs_ct_execute() when the
netns is torn down.

Publish the CT limit pointer through RCU, remove it before teardown, and
wait for readers before freeing its contents. Keep ovs_mutex around
individual CT limit updates, and use the RCU read-side lock while GET
traverses the RCU-protected limit lists.

Netns teardown detaches the RCU-protected CT limit state in the pernet
.pre_exit callback while holding ovs_mutex.  The pernet core guarantees an
RCU grace period between the .pre_exit and .exit callbacks, so the .exit
callback completes the teardown without adding any extra synchronization.

The netlink command handlers do not need NULL checks because the userspace
netlink socket holds an active reference to its network namespace while a
request is processed. The per-netns exit path therefore cannot run
concurrently with SET, DEL, or GET for that socket's namespace.

## Affected

- `Linux >= 11efd5cb04a184eea4f57b68ea63dddd463158d1 < 239f26589a6926db28c436e14f28517581ef1385`
- `Linux >= 11efd5cb04a184eea4f57b68ea63dddd463158d1 < 3b9369881b403f4cdbb11fa998554382bdcc3d8c`
- `Linux >= 11efd5cb04a184eea4f57b68ea63dddd463158d1 < 3b41d907400cc1dd1da9555b81dca422b1f44433`
- `Linux >= 11efd5cb04a184eea4f57b68ea63dddd463158d1 < 680f20d5937fa4d1367c59fe83091b78041015f5`
- `Linux >= 11efd5cb04a184eea4f57b68ea63dddd463158d1 < bf4aaa7ea2579e24ed7de2e20578a875bebca011`
- `Linux >= 11efd5cb04a184eea4f57b68ea63dddd463158d1 < e15407c3a8a005324f633cd46cd8fb58042c1157`
- `Linux >= 11efd5cb04a184eea4f57b68ea63dddd463158d1 < 6a6d36fadb8537d9b79e72c9fa51885ec0c33e10`
- `Linux >= 11efd5cb04a184eea4f57b68ea63dddd463158d1 < 403f96c32c9e24600093d7d0c61c17daeedca957`
- `Linux 4.18`

## Remediation

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

## Vendor advisories

- **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4, Red Hat Enterprise Linux 6 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-09-18 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89488.json)