CVE Vulnerabilities

CVE-2021-26866

Improper Link Resolution Before File Access ('Link Following')

Published: Mar 11, 2021 | Modified: May 03, 2022
CVSS 3.x
6.1
MEDIUM
Source:
NVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H
CVSS 2.x
3.6 LOW
AV:L/AC:L/Au:N/C:N/I:P/A:P
RedHat/V2
RedHat/V3
Ubuntu

Windows Update Service Elevation of Privilege Vulnerability

Weakness

The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

Affected Software

Name Vendor Start Version End Version
Windows_10 Microsoft 1607 1607
Windows_server_2016 Microsoft - -
Windows_10 Microsoft - -
Windows_10 Microsoft 1803 1803
Windows_server_2019 Microsoft - -
Windows_10 Microsoft 1809 1809
Windows_server_2016 Microsoft 1909 1909
Windows_10 Microsoft 1909 1909
Windows_10 Microsoft 2004 2004
Windows_server_2016 Microsoft 2004 2004
Windows_10 Microsoft 20h2 20h2
Windows_server_2016 Microsoft 20h2 20h2

Potential Mitigations

  • Follow the principle of least privilege when assigning access rights to entities in a software system.
  • Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.

References