NVD

CVE-2021-26887 Detail

Modified

This CVE record has been updated after NVD enrichment efforts were completed. Enrichment data supplied by the NVD may require amendment due to these changes.

Current Description

An elevation of privilege vulnerability exists in Microsoft Windows when Folder redirection has been enabled via Group Policy. When folder redirection file server is co-located with Terminal server, an attacker who successfully exploited the vulnerability would be able to begin redirecting another user's personal data to a created folder. To exploit the vulnerability, an attacker can create a new folder under the Folder Redirection root path and create a junction on a newly created User folder. When the new user logs in, Folder Redirection would start redirecting to the folder and copying personal data. This elevation of privilege vulnerability can only be addressed by reconfiguring Folder Redirection with Offline files and restricting permissions, and NOT via a security update for affected Windows Servers. See the FAQ section of this CVE for configuration guidance.

View Analysis Description

Metrics

NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.

CVSS 4.0 Severity and Vector Strings:

NIST: NVD

N/A

NVD assessment not yet provided.

CVSS 3.x Severity and Vector Strings:

CNA: Microsoft Corporation

Base Score: 7.8 HIGH

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

CVSS 2.0 Severity and Vector Strings:

National Institute of Standards and Technology

NIST: NVD

Base Score: 4.6 MEDIUM

Vector: (AV:L/AC:L/Au:N/C:P/I:P/A:P)

References to Advisories, Solutions, and Tools

By selecting these links, you will be leaving NIST webspace. We have provided these links to other web sites because they may have information that would be of interest to you. No inferences should be drawn on account of other sites being referenced, or not, from this page. There may be other web sites that are more appropriate for your purpose. NIST does not necessarily endorse the views expressed, or concur with the facts presented on these sites. Further, NIST does not endorse any commercial products that may be mentioned on these sites. Please address comments about this page to [email protected].

URL	Source(s)	Tag(s)
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26887	CVE, Microsoft Corporation	Patch Vendor Advisory

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-59	Improper Link Resolution Before File Access ('Link Following')	NIST

Known Affected Software Configurations Switch to CPE 2.2

CPEs loading, please wait.

Denotes Vulnerable Software
Are we missing a CPE here? Please let us know.

Change History

6 change records found show changes

CVE Modified by Microsoft Corporation 2/24/2026 11:23:27 AM

Action

Type

Old Value

New Value

Changed

Description

<p>An elevation of privilege vulnerability exists in Microsoft Windows when Folder redirection has been enabled via Group Policy. When folder redirection file server is co-located with Terminal server, an attacker who successfully exploited the vulnerability would be able to begin redirecting another user's personal data to a created folder.</p>
<p>To exploit the vulnerability, an attacker can create a new folder under the Folder Redirection root path and create a junction on a newly created User folder. When the new user logs in, Folder Redirection would start redirecting to the folder and copying personal data.</p>
<p>This elevation of privilege vulnerability can only be addressed by reconfiguring Folder Redirection with Offline files and restricting permissions, and NOT via a security update for affected Windows Servers. See the <strong>FAQ</strong> section of this CVE for configuration guidance.</p>

<p>An elevation of privilege vulnerability exists in Microsoft Windows when Folder redirection has been enabled via Group Policy. When folder redirection file server is co-located with Terminal server, an attacker who successfully exploited the vulnerability would be able to begin redirecting another user's personal data to a created folder.</p>
<p>To exploit the vulnerability, an attacker can create a new folder under the Folder Redirection root path and create a junction on a newly created User folder. When the new user logs in, Folder Redirection would start redirecting to the folder and copying personal data.</p>
<p>This elevation of privilege vulnerability can only be addressed by reconfiguring Folder Redirection with Offline files and restricting permissions, and NOT via a security update for affected Windows Servers. See the <strong>FAQ</strong> section of this CVE for configuration guidance.</p>

Initial Analysis by NIST 3/12/2021 4:34:17 PM

Action	Type	Old Value	New Value
Added	CVSS V3.1		NIST AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Added	CVSS V2		NIST (AV:L/AC:L/Au:N/C:P/I:P/A:P)
Added	CWE		NIST CWE-269
Added	CPE Configuration		OR cpe:2.3:o:microsoft:windows_10:-::::::: cpe:2.3:o:microsoft:windows_10:20h2::::::: cpe:2.3:o:microsoft:windows_10:1607::::::: cpe:2.3:o:microsoft:windows_10:1803::::::: cpe:2.3:o:microsoft:windows_10:1809::::::: cpe:2.3:o:microsoft:windows_10:1909::::::: cpe:2.3:o:microsoft:windows_10:2004::::::: cpe:2.3:o:microsoft:windows_7:-:sp1::::::* cpe:2.3:o:microsoft:windows_8.1:-::::::: cpe:2.3:o:microsoft:windows_rt_8.1:-::::::: cpe:2.3:o:microsoft:windows_server_2008:-:sp2::::::* cpe:2.3:o:microsoft:windows_server_2008:r2:sp1:::::x64: cpe:2.3:o:microsoft:windows_server_2012:-::::::: cpe:2.3:o:microsoft:windows_server_2012:r2::::::: cpe:2.3:o:microsoft:windows_server_2016:-::::::: cpe:2.3:o:microsoft:windows_server_2016:20h2::::::: cpe:2.3:o:microsoft:windows_server_2016:1909::::::: cpe:2.3:o:microsoft:windows_server_2016:2004::::::: cpe:2.3:o:microsoft:windows_server_2019:-:::::::
Changed	Reference Type	https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26887 No Types Assigned	https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26887 Patch, Vendor Advisory

Quick Info

CVE Dictionary Entry:
CVE-2021-26887
NVD Published Date:
03/11/2021
NVD Last Modified:
02/24/2026
Source:
Microsoft Corporation

You are viewing this page in an unauthorized frame window.

Information Technology Laboratory

National Vulnerability Database

National Vulnerability Database

CVE-2021-26887 Detail

Current Description

Analysis Description

Metrics

References to Advisories, Solutions, and Tools

Weakness Enumeration

Known Affected Software Configurations Switch to CPE 2.2

CPEs loading, please wait.

Change History

CVE Modified by Microsoft Corporation 2/24/2026 11:23:27 AM

CVE Modified by CVE 11/21/2024 12:56:58 AM

CVE Modified by Microsoft Corporation 5/14/2024 4:36:49 AM

CVE Modified by Microsoft Corporation 12/29/2023 3:15:55 PM

CWE Remap by NIST 5/03/2022 12:04:40 PM

Initial Analysis by NIST 3/12/2021 4:34:17 PM

Quick Info