CVE-2021-42378: A use-after-free in Busybox's awk applet leads to denial of service and possibly code execution when processing a crafted awk pattern in the getvar_i function

Overview

Severity
High (CVSS 7.2)
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Exploit Status
Not Exploited
Patch Tuesday
2021-Nov
Released
2021-11-18
Last Updated
2021-12-16
EPSS Score
0.24% (percentile: 46.6%)

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

  • 18965-16820
  • 18966-16823

Revision History

  • 2021-11-18: Information published.
  • 2021-12-16: Added busybox to CBL-Mariner 2.0