---
id: CVE-2026-89743
title: 'misc: nsm: bound the device-reported response length'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  misc: nsm: bound the device-reported response length

  nsm_sendrecv_msg_locked() stores the virtqueue used-ring length reported
  by the NSM device into msg->resp.len with…
severity: high
cvss: 7.7
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-125
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= b9873755a6c8ccfce79094c4dce9efa3ecb1a749 <
    339f19b9a6171289b0e797deb8bda80b9a1fcc30
  - >-
    Linux >= b9873755a6c8ccfce79094c4dce9efa3ecb1a749 <
    29e634a18957acda11383a15ab98a91c4ae9e294
  - >-
    Linux >= b9873755a6c8ccfce79094c4dce9efa3ecb1a749 <
    2aa0fb9c96f894a9c179a48e7522ea6705800adf
  - >-
    Linux >= b9873755a6c8ccfce79094c4dce9efa3ecb1a749 <
    808e530654a5354e6df78863a5d61e4d44e67235
  - Linux 6.8
published: '2026-09-11'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T08:51:57.186Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-89743'
references:
  - url: 'https://git.kernel.org/stable/c/339f19b9a6171289b0e797deb8bda80b9a1fcc30'
  - url: 'https://git.kernel.org/stable/c/29e634a18957acda11383a15ab98a91c4ae9e294'
  - url: 'https://git.kernel.org/stable/c/2aa0fb9c96f894a9c179a48e7522ea6705800adf'
  - url: 'https://git.kernel.org/stable/c/808e530654a5354e6df78863a5d61e4d44e67235'
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89743.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89743'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532206'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89743'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89743'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89743.mbox
tags:
  - cve.org
  - csaf
  - vex
  - red-hat
  - score-dispute
epss: 0.00142
epssPercentile: 0.03451
scores:
  cna: 7.7
  vendor: 5.5
ingestedAt: '2026-09-14T15:23:07.472Z'
---

## Overview

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

misc: nsm: bound the device-reported response length

nsm_sendrecv_msg_locked() stores the virtqueue used-ring length reported
by the NSM device into msg->resp.len without bounding it to the response
buffer. A malicious or buggy backend can report a length larger than the
response buffer; parse_resp_raw() then copies that many bytes out of the
fixed buffer to user space, disclosing adjacent kernel heap (an
out-of-bounds read). The request path already floors its length in
fill_req_raw(); the response path lacks the symmetric check.

Clamp the stored length to the size of the response buffer. Well-behaved
devices report no more than the posted buffer size, so conforming traffic
is unaffected.

## Affected

- `Linux >= b9873755a6c8ccfce79094c4dce9efa3ecb1a749 < 339f19b9a6171289b0e797deb8bda80b9a1fcc30`
- `Linux >= b9873755a6c8ccfce79094c4dce9efa3ecb1a749 < 29e634a18957acda11383a15ab98a91c4ae9e294`
- `Linux >= b9873755a6c8ccfce79094c4dce9efa3ecb1a749 < 2aa0fb9c96f894a9c179a48e7522ea6705800adf`
- `Linux >= b9873755a6c8ccfce79094c4dce9efa3ecb1a749 < 808e530654a5354e6df78863a5d61e4d44e67235`
- `Linux 6.8`

## Remediation

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

## Vendor advisories

- **Red Hat VEX** · Moderate · updated 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89743.json)