---
id: CVE-2021-28691
title: >-
  Guest triggered use-after-free in Linux xen-netback A malicious or buggy
  network PV frontend can force Linux netback to disable the interface and
  terminate the receive kernel thread associated with queue 0 in response to the
  frontend sen…
summary: >-
  Guest triggered use-after-free in Linux xen-netback A malicious or buggy
  network PV frontend can force Linux netback to disable the interface and
  terminate the receive kernel thread associated with queue 0 in response to the
  frontend sen…
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-416
vendor: netapp
product: solidfire_baseboard_management_controller
affected:
  - solidfire_baseboard_management_controller
  - 'linux_kernel >= 5.5.0, < 5.10.43'
  - cloud_backup
  - h410c_firmware
  - h300s_firmware
  - h500s_firmware
  - h700s_firmware
  - h300e_firmware
  - h500e_firmware
  - h700e_firmware
  - h410s_firmware
patched:
  - linux_kernel 5.10.43
published: '2021-06-29'
updated: '2026-08-26'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-28691'
references:
  - url: 'https://security.gentoo.org/glsa/202107-30'
    label: security@xen.org
  - url: 'https://security.netapp.com/advisory/ntap-20210805-0002/'
    label: security@xen.org
  - url: 'https://xenbits.xenproject.org/xsa/advisory-374.txt'
    label: security@xen.org
  - url: 'https://security.gentoo.org/glsa/202107-30'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.netapp.com/advisory/ntap-20210805-0002/'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://xenbits.xenproject.org/xsa/advisory-374.txt'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.00361
epssPercentile: 0.27241
ingestedAt: '2026-08-26T18:47:53.472Z'
---

## Overview

Guest triggered use-after-free in Linux xen-netback A malicious or buggy network PV frontend can force Linux netback to disable the interface and terminate the receive kernel thread associated with queue 0 in response to the frontend sending a malformed packet. Such kernel thread termination will lead to a use-after-free in Linux netback when the backend is destroyed, as the kernel thread associated with queue 0 will have already exited and thus the call to kthread_stop will be performed against a stale pointer.

## Affected

- `solidfire_baseboard_management_controller`
- `linux_kernel >= 5.5.0, < 5.10.43`
- `cloud_backup`
- `h410c_firmware`
- `h300s_firmware`
- `h500s_firmware`
- `h700s_firmware`
- `h300e_firmware`
- `h500e_firmware`
- `h700e_firmware`
- `h410s_firmware`

## Remediation

Upgrade past the affected range:

- `linux_kernel 5.10.43`