---
id: CVE-2021-20320
title: >-
  A flaw was found in s390 eBPF JIT in bpf_jit_insn in
  arch/s390/net/bpf_jit_comp.c in the Linux kernel
summary: >-
  A flaw was found in s390 eBPF JIT in bpf_jit_insn in
  arch/s390/net/bpf_jit_comp.c in the Linux kernel. In this flaw, a local
  attacker with special user privilege can circumvent the verifier and may lead
  to a confidentiality problem.
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
vendor: linux
product: linux_kernel
affected:
  - linux_kernel < 5.15
  - linux_kernel = 5.15
  - fedora = 34
  - enterprise_linux = 7.0
  - enterprise_linux = 8.0
patched:
  - linux_kernel 5.15
published: '2022-02-18'
updated: '2026-10-08'
sourceUpdated: '2026-10-08T21:17:33.553'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-20320'
references:
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2010090'
    label: secalert@redhat.com
  - url: >-
      https://lore.kernel.org/bpf/20210902185229.1840281-1-johan.almbladh%40anyfinetworks.com/
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2010090'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lore.kernel.org/bpf/20210902185229.1840281-1-johan.almbladh%40anyfinetworks.com/
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.0026
epssPercentile: 0.16289
ingestedAt: '2026-10-08T22:11:53.747Z'
---

## Overview

A flaw was found in s390 eBPF JIT in bpf_jit_insn in arch/s390/net/bpf_jit_comp.c in the Linux kernel. In this flaw, a local attacker with special user privilege can circumvent the verifier and may lead to a confidentiality problem.

## Affected

- `linux_kernel < 5.15`
- `linux_kernel = 5.15`
- `fedora = 34`
- `enterprise_linux = 7.0`
- `enterprise_linux = 8.0`

## Remediation

Upgrade past the affected range:

- `linux_kernel 5.15`