CVE-2021-3981

Local password disclosure via world-readable configuration

Published Mar 8, 2022 · Updated Feb 13, 2025

Incorrect permissions in GNU GRUB 2.06 and earlier allow local users to read passwords from grub.cfg after configuration generation. grub-mkconfig loses its restrictive umask and creates grub.cfg with mode 0644 instead of 0600. A low-privileged local account can read any encrypted or plaintext bootloader passwords stored in the generated file.

CVSS severity3.3
Low
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect permissions in GNU GRUB 2.06 and earlier allow local users to read passwords from grub.cfg after configuration generation. grub-mkconfig loses its restrictive umask and creates grub.cfg with mode 0644 instead of 0600. A low-privileged local account can read any encrypted or plaintext bootloader passwords stored in the generated file.

The record

CVE
CVE-2021-3981
Published
Mar 8, 2022
Updated
Feb 13, 2025
Vendor
The GnuPG Project
Product
GNU GRUB
Classifications
CWE-276, T1552.001
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 8, 2022CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=grub2 2.06 and previous versions

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The GnuPG Project · GNU GRUBversion=grub2 2.06 and previous versions

Published CVSS scores

3.3NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
3.3SUSECVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
2.1NIST NVDAV:L/AC:L/Au:N/C:P/I:N/A:N
3.3Canonical UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-276Incorrect Default Permissions
T1552.001Credentials In Files

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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