// For flags

CVE-2021-26889

Windows Update Stack Elevation of Privilege Vulnerability

Severity Score

7.8
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

-
*SSVC
Descriptions

Windows Update Stack Elevation of Privilege Vulnerability

Una Vulnerabilidad de ElevaciĆ³n de Privilegios de la Pila de Windows Update

This vulnerability allows local attackers to escalate privileges on affected installations of Microsoft Windows. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.
The specific flaw exists within Windows Setup. By creating a directory junction, an attacker can abuse Windows Setup to create a file in an arbitrary location. An attacker can leverage this vulnerability to escalate privileges and execute code in the context of SYSTEM.

*Credits: Abdelhamid Naceri (halov)
CVSS Scores
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Attack Vector
Local
Attack Complexity
Low
Authentication
None
Confidentiality
Partial
Integrity
Partial
Availability
Partial
* Common Vulnerability Scoring System
SSVC
  • Decision:-
Exploitation
-
Automatable
-
Tech. Impact
-
* Organization's Worst-case Scenario
Timeline
  • 2021-02-08 CVE Reserved
  • 2021-03-11 CVE Published
  • 2024-08-03 CVE Updated
  • 2024-10-06 EPSS Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-59: Improper Link Resolution Before File Access ('Link Following')
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Microsoft
Search vendor "Microsoft"
Windows 10
Search vendor "Microsoft" for product "Windows 10"
20h2
Search vendor "Microsoft" for product "Windows 10" and version "20h2"
-
Affected
Microsoft
Search vendor "Microsoft"
Windows 10
Search vendor "Microsoft" for product "Windows 10"
1803
Search vendor "Microsoft" for product "Windows 10" and version "1803"
-
Affected
Microsoft
Search vendor "Microsoft"
Windows 10
Search vendor "Microsoft" for product "Windows 10"
1809
Search vendor "Microsoft" for product "Windows 10" and version "1809"
-
Affected
Microsoft
Search vendor "Microsoft"
Windows 10
Search vendor "Microsoft" for product "Windows 10"
1909
Search vendor "Microsoft" for product "Windows 10" and version "1909"
-
Affected
Microsoft
Search vendor "Microsoft"
Windows 10
Search vendor "Microsoft" for product "Windows 10"
2004
Search vendor "Microsoft" for product "Windows 10" and version "2004"
-
Affected
Microsoft
Search vendor "Microsoft"
Windows Server 2016
Search vendor "Microsoft" for product "Windows Server 2016"
20h2
Search vendor "Microsoft" for product "Windows Server 2016" and version "20h2"
-
Affected
Microsoft
Search vendor "Microsoft"
Windows Server 2016
Search vendor "Microsoft" for product "Windows Server 2016"
1909
Search vendor "Microsoft" for product "Windows Server 2016" and version "1909"
-
Affected
Microsoft
Search vendor "Microsoft"
Windows Server 2016
Search vendor "Microsoft" for product "Windows Server 2016"
2004
Search vendor "Microsoft" for product "Windows Server 2016" and version "2004"
-
Affected
Microsoft
Search vendor "Microsoft"
Windows Server 2019
Search vendor "Microsoft" for product "Windows Server 2019"
--
Affected