CVE-2021-20225: A flaw was found in grub2 in versions prior to 2.06. The option parser allows an attacker to write past the end of a heap-allocated buffer by calling certain commands with a large number of specific short forms of options. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

Overview

Severity

Medium (CVSS 6.7)

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Exploit Status

Not Exploited

Patch Tuesday

2021-Mar

Released

2021-03-11

Last Updated

2026-02-26

EPSS Score

0.07% (percentile: 21.5%)

FAQ

Is Azure Linux the only Microsoft product that includes this open-source library and is therefore potentially affected by this vulnerability? One of the main benefits to our customers who choose to use the Azure Linux distro is the commitment to keep it up to date with the most recent and most secure versions of the open source libraries with which the distro is composed. Microsoft is committed to transparency in this work which is why we began publishing CSAF/VEX in October 2025. See this blog post for more information. If impact to additional products is identified, we will update the CVE to reflect this.

Affected Products (2)

Other

• 19072-16823
• 20796-17084

Revision History

• 2021-03-11: Information published.
• 2021-12-16: Added grub2 to CBL-Mariner 2.0
• 2026-02-26: Information published.