---
id: CVE-2021-4135
title: >-
  A memory leak vulnerability was found in the Linux kernel's eBPF for the
  Simulated networking device driver in the way user uses BPF for the device
  such that function nsim_map_alloc_elem being called
summary: >-
  A memory leak vulnerability was found in the Linux kernel's eBPF for the
  Simulated networking device driver in the way user uses BPF for the device
  such that function nsim_map_alloc_elem being called. A local user could use
  this flaw to …
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N'
cwe:
  - CWE-200
  - CWE-401
vendor: linux
product: linux_kernel
affected:
  - linux_kernel < 5.16
  - linux_kernel = 5.16
patched:
  - linux_kernel 5.16
published: '2022-07-14'
updated: '2026-10-08'
sourceUpdated: '2026-10-08T21:17:42.743'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-4135'
references:
  - url: >-
      https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=481221775d53
    label: secalert@redhat.com
  - url: >-
      https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=481221775d53
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.00231
epssPercentile: 0.12849
ingestedAt: '2026-10-08T22:11:53.758Z'
---

## Overview

A memory leak vulnerability was found in the Linux kernel's eBPF for the Simulated networking device driver in the way user uses BPF for the device such that function nsim_map_alloc_elem being called. A local user could use this flaw to get unauthorized access to some data.

## Affected

- `linux_kernel < 5.16`
- `linux_kernel = 5.16`

## Remediation

Upgrade past the affected range:

- `linux_kernel 5.16`