Skip to content
Fencer Vulns
low 3.3

CVE-2021-3981 json

A flaw in grub2 was found where its configuration file, known as grub.cfg, is being created with the wrong permission set allowing non priv…

published 2022-03-08 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-27182

cvss
3.3
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 25%
public exploits
0
none known

Summary

A flaw in grub2 was found where its configuration file, known as grub.cfg, is being created with the wrong permission set allowing non privileged users to read its content. This represents a low severity confidentiality issue, as those users can eventually read any encrypted passwords present in grub.cfg. This flaw affects grub2 2.06 and previous versions. This issue has been fixed in grub upstream but no version with the fix is currently released.

Patch / fix

  • grub2 Debian 14, Debian 13, Debian 12 2.06-8

debian advisories DEBIAN-CVE-2021-3981

  • grub2-signed Ubuntu 20.04 LTS 1.187.3~20.04.1
  • grub2-signed Ubuntu 22.04 LTS 1.187.3~22.04.1
  • grub2-unsigned Ubuntu 22.04 LTS, Ubuntu 20.04 LTS 2.06-2ubuntu14.1

ubuntu advisories UBUNTU-CVE-2021-3981

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • grub2 RHEL 8 1:2.02-123.el8
  • grub2-pc RHEL 8 1:2.02-123.el8
  • grub2-tools RHEL 8 1:2.02-123.el8
  • grub2-common RHEL 8 1:2.02-123.el8
  • grub2-efi-x64 RHEL 8 1:2.02-123.el8
  • grub2-ppc64le RHEL 8 1:2.02-123.el8
  • grub2-efi-aa64 RHEL 8 1:2.02-123.el8
  • grub2-efi-ia32 RHEL 8 1:2.02-123.el8

red hat advisories RHSA-2022:2110

  • grub2 openSUSE Tumbleweed 2.06-13.1

opensuse advisories openSUSE-SU-2024:11700-1

  • grub2-pc AlmaLinux 8 1:2.02-123.el8.alma
  • grub2-tools AlmaLinux 8 1:2.02-123.el8.alma
  • grub2-common AlmaLinux 8 1:2.02-123.el8.alma
  • grub2-efi-x64 AlmaLinux 8 1:2.02-123.el8.alma
  • grub2-ppc64le AlmaLinux 8 1:2.02-123.el8_6.8.alma
  • grub2-efi-aa64 AlmaLinux 8 1:2.02-123.el8.alma
  • grub2-efi-ia32 AlmaLinux 8 1:2.02-123.el8.alma
  • grub2-tools-efi AlmaLinux 8 1:2.02-123.el8.alma

almalinux advisories ALSA-2022:2110

  • grub2 Rocky Linux 8 1:2.02-123.el8

rocky linux advisories RLSA-2022:2110

  • grub2 Azure Linux 3.0 2.06-14
  • grub2 CBL-Mariner 2.0 2.06-5

azure linux advisories AZL-34786AZL-8937

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-3981 updated cvss 3.3

grub2: Incorrect permission in grub.cfg allow unprivileged user to read the file content

  • Red Hat Enterprise Linux 7 grub2, grub2-pc, grub2-efi, grub2-ppc64, grub2-tools, grub2-common, +15 more
    affected: no fix available
  • Red Hat Enterprise Linux BaseOS (v. 8) grub2 2.02-123.el8, grub2-pc 2.02-123.el8, grub2-tools 2.02-123.el8, grub2-common 2.02-123.el8, grub2-efi-x64 2.02-123.el8, grub2-ppc64le 2.02-123.el8, +13 more
    fixed: vendor fix RHSA-2022:2110
  • Red Hat Enterprise Linux 9 grub2, grub2-pc, grub2-tools, grub2-common, grub2-efi-x64, grub2-ppc64le, +10 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.32% chance of exploitation in the next 30 days, higher than 25% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 3.3 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
NVD 2.0 2.1 AV:L/AC:L/Au:N/C:P/I:N/A:N

Affected products

  • n/a grub2

Classification

Weakness
  • CWE-276 Incorrect Default Permissions

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.