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TI-2021-08495 Aliases CVE-2021-26887GHSA-xphp-jrmh-9rjj

Microsoft Windows Folder Redirection Elevation of Privilege Vulnerability

Priority LOW 38CWE-59Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Privilege escalation
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Microsoft. Impact type from Microsoft.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.01065 64th percentileScored 2026-11-07
Fix Fixed Microsoft: 2 updates

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
MicrosoftWindows 10 Version 1507-—No fix listedCNA
MicrosoftWindows 10 Version 1607-—No fix listedCNA
MicrosoftWindows 10 Version 1803-—No fix listedCNA
MicrosoftWindows 10 Version 1809-—No fix listedCNA
MicrosoftWindows 10 Version 1809-—No fix listedCNA
MicrosoftWindows 10 Version 1909-—No fix listedCNA
MicrosoftWindows 10 Version 2004-—No fix listedCNA
MicrosoftWindows 10 Version 20H2-—No fix listedCNA
MicrosoftWindows 7-—No fix listedCNA
MicrosoftWindows 7 Service Pack 1-—No fix listedCNA
MicrosoftWindows 8.1-—No fix listedCNA
MicrosoftWindows Server 2008 R2 Service Pack 1-—No fix listedCNA
MicrosoftWindows Server 2008 R2 Service Pack 1 (Server Core installation)-—No fix listedCNA
MicrosoftWindows Server 2008 Service Pack 2-—No fix listedCNA
MicrosoftWindows Server 2008 Service Pack 2 (Server Core installation)-—No fix listedCNA
MicrosoftWindows Server 20126.2.9200.0 to before 6.2.9200.232986.2.9200.23298Patch availableCNA
MicrosoftWindows Server 2012 (Server Core installation)6.2.9200.0 to before 6.2.9200.232986.2.9200.23298Patch availableCNA
MicrosoftWindows Server 2012 R2-—No fix listedCNA
MicrosoftWindows Server 2012 R2 (Server Core installation)-—No fix listedCNA
MicrosoftWindows Server 2016-—No fix listedCNA
MicrosoftWindows Server 2016 (Server Core installation)-—No fix listedCNA
MicrosoftWindows Server 2019-—No fix listedCNA
MicrosoftWindows Server 2019 (Server Core installation)-—No fix listedCNA
MicrosoftWindows Server version 2004-—No fix listedCNA
MicrosoftWindows Server version 20H2-—No fix listedCNA
MicrosoftWindows Server, version 1909 (Server Core installation)-—No fix listedCNA
  • Windows 10 Version 1507 VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows 10 Version 1607 VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows 10 Version 1803 VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows 10 Version 1809 VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows 10 Version 1809 VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows 10 Version 1909 VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows 10 Version 2004 VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows 10 Version 20H2 VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows 7 VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows 7 Service Pack 1 VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows 8.1 VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows Server 2008 R2 Service Pack 1 VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows Server 2008 R2 Service Pack 1 (Server Core installation) VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows Server 2008 Service Pack 2 VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows Server 2008 Service Pack 2 (Server Core installation) VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows Server 2012 VendorMicrosoft Affected 6.2.9200.0 to before 6.2.9200.23298 Fixed in 6.2.9200.23298 Patch available CNA
  • Windows Server 2012 (Server Core installation) VendorMicrosoft Affected 6.2.9200.0 to before 6.2.9200.23298 Fixed in 6.2.9200.23298 Patch available CNA
  • Windows Server 2012 R2 VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows Server 2012 R2 (Server Core installation) VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows Server 2016 VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows Server 2016 (Server Core installation) VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows Server 2019 VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows Server 2019 (Server Core installation) VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows Server version 2004 VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows Server version 20H2 VendorMicrosoft Affected - Fixed in — No fix listed CNA
  • Windows Server, version 1909 (Server Core installation) VendorMicrosoft Affected - Fixed in — No fix listed CNA

CPE configurations NVD · 19

CPEVersionsRoleVendor
cpe:2.3:o:microsoft:windows_10:-:*:*:*:*:*:*:*not specified by NVDVulnerableMicrosoft
cpe:2.3:o:microsoft:windows_10:20h2:*:*:*:*:*:*:*20h2VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_10:1607:*:*:*:*:*:*:*1607VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_10:1803:*:*:*:*:*:*:*1803VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_10:1809:*:*:*:*:*:*:*1809VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_10:1909:*:*:*:*:*:*:*1909VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_10:2004:*:*:*:*:*:*:*2004VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_7:-:sp1:*:*:*:*:*:*not specified by NVDVulnerableMicrosoft
cpe:2.3:o:microsoft:windows_8.1:-:*:*:*:*:*:*:*not specified by NVDVulnerableMicrosoft
cpe:2.3:o:microsoft:windows_rt_8.1:-:*:*:*:*:*:*:*not specified by NVDVulnerableMicrosoft
  • cpe:2.3:o:microsoft:windows_10:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_10:20h2:*:*:*:*:*:*:* Versions 20h2 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_10:1607:*:*:*:*:*:*:* Versions 1607 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_10:1803:*:*:*:*:*:*:* Versions 1803 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_10:1809:*:*:*:*:*:*:* Versions 1809 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_10:1909:*:*:*:*:*:*:* Versions 1909 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_10:2004:*:*:*:*:*:*:* Versions 2004 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_7:-:sp1:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_8.1:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_rt_8.1:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Microsoft
Show 9 more CPE
CPEVersionsRoleVendor
cpe:2.3:o:microsoft:windows_server_2008:-:sp2:*:*:*:*:*:*not specified by NVDVulnerableMicrosoft
cpe:2.3:o:microsoft:windows_server_2008:r2:sp1:*:*:*:*:x64:*r2 sp1VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_server_2012:-:*:*:*:*:*:*:*not specified by NVDVulnerableMicrosoft
cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:*r2VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_server_2016:-:*:*:*:*:*:*:*not specified by NVDVulnerableMicrosoft
cpe:2.3:o:microsoft:windows_server_2016:20h2:*:*:*:*:*:*:*20h2VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_server_2016:1909:*:*:*:*:*:*:*1909VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_server_2016:2004:*:*:*:*:*:*:*2004VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_server_2019:-:*:*:*:*:*:*:*not specified by NVDVulnerableMicrosoft
  • cpe:2.3:o:microsoft:windows_server_2008:-:sp2:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_server_2008:r2:sp1:*:*:*:*:x64:* Versions r2 sp1 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_server_2012:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:* Versions r2 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_server_2016:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_server_2016:20h2:*:*:*:*:*:*:* Versions 20h2 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_server_2016:1909:*:*:*:*:*:*:* Versions 1909 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_server_2016:2004:*:*:*:*:*:*:* Versions 2004 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_server_2019:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Microsoft

Remediation

Microsoft 2 updates

  • KB5000847
    Monthly Rollup
    • Internet Explorer 11 6.2.9200.23298
    • Windows Server 2012 6.2.9200.23298
    • Windows Server 2012 (Server Core installation) 6.2.9200.23298
  • KB5000840
    https
    • Windows Server 2012 Security Only
    • Windows Server 2012 (Server Core installation) Security Only

Vendor assessments

Microsoft

Microsoft's page for this CVE →

Impact
Elevation of Privilege
Exploited
No
Publicly disclosed
No
Exploitability
Exploitation Less Likely
ProductStatusPlan or fix
1AffectedNo update listed
10AffectedNo update listed
11AffectedNo update listed
12AffectedNo update listed
13AffectedNo update listed
14AffectedNo update listed
15AffectedNo update listed
16AffectedNo update listed
17AffectedNo update listed
18AffectedNo update listed
19AffectedNo update listed
2AffectedNo update listed
20AffectedNo update listed
21AffectedNo update listed
22AffectedNo update listed
23AffectedNo update listed
24AffectedNo update listed
25AffectedNo update listed
26AffectedNo update listed
27AffectedNo update listed
28AffectedNo update listed
29AffectedNo update listed
3AffectedNo update listed
30AffectedNo update listed
33AffectedNo update listed
34AffectedNo update listed
35AffectedNo update listed
36AffectedNo update listed
37AffectedNo update listed
38AffectedNo update listed
39AffectedNo update listed
4AffectedNo update listed
40AffectedNo update listed
5AffectedNo update listed
6AffectedNo update listed
7AffectedNo update listed
8AffectedNo update listed
9AffectedNo update listed

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-26887
  2. 2026-10-03 Alias added: GHSA-xphp-jrmh-9rjj

References

Patch 2

  • TI-2015-02132 Buffer underflow in atmfd.dll in the Windows Adobe Type Manager Library in Microsoft… KEVCVSS 3.1HIGH 8.8
  • TI-2022-10056 Remote Procedure Call Runtime Remote Code Execution Vulnerability CVSS 3.1CRITICAL 9.8
  • TI-2022-06273 HTTP Protocol Stack Remote Code Execution Vulnerability CVSS 3.1CRITICAL 9.8
  • TI-2019-00906 Remote Desktop Services Remote Code Execution Vulnerability CVSS 3.1CRITICAL 9.8
  • TI-2022-15533 Windows Internet Key Exchange (IKE) Protocol Extensions Remote Code Execution Vulnerability CVSS 3.1CRITICAL 9.8
  • TI-2015-01587 Mount Manager in Microsoft Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows… KEVCVSS 3.1MEDIUM 6.6
See all 2973 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences