CVE-2021-26873: Microsoft Windows User Profile Service Directory Junction Privilege Escalation Vulnerability
Windows User Profile Service Elevation of Privilege Vulnerability
Other sources
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 the User Profile Service. By creating a directory junction, an attacker can abuse the service to create a second junction in a sensitive location. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of SYSTEM.
— ZDI
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 6.2.9200.23298Patch KB5000840 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 6.3.9600.19968Patch KB5000853 - Upgrade
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Fixed in 6.1.7601.24566Patch KB5000851 - Upgrade
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Fixed in 6.0.6003.21070Patch KB5000856 - Upgrade
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Fixed in 6.3.9600.19968Patch KB5000848 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.14393.4283Patch KB5000803 - Upgrade
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Fixed in 10.0.10240.18874Patch KB5000807 - Upgrade
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Fixed in 10.0.19043.867Patch KB5000802 - Upgrade
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Fixed in 10.0.18363.1440Patch KB5000808 - Upgrade
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Fixed in 10.0.17763.1817Patch KB5000822 - Upgrade
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Fixed in 10.0.17134.2087Patch KB5000809
Event History
Frequently Asked Questions
What is the severity of CVE-2021-26873?
CVE-2021-26873 has a severity rating of Important, allowing local attackers to escalate privileges.
How do I fix CVE-2021-26873?
To fix CVE-2021-26873, apply the appropriate security updates released by Microsoft for the affected Windows versions.
Which versions of Windows are affected by CVE-2021-26873?
CVE-2021-26873 affects various versions of Windows including Windows 7, 10, and Windows Server editions.
Can CVE-2021-26873 be exploited remotely?
CVE-2021-26873 cannot be exploited remotely and requires local access to the affected system.
Is there a workaround for CVE-2021-26873?
There are no specific workarounds for CVE-2021-26873; applying the security updates is the recommended mitigation method.