CVE-2021-26887

HIGH

Windows - Elevation of Privilege via Folder Redirection Junction

Title source: llm
STIX 2.1

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>

References (1)

Core 1
Core References

Scores

CVSS v3 7.8
EPSS 0.0092
EPSS Percentile 55.6%
Attack Vector LOCAL
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact total

Details

CWE
CWE-59
Status published
Products (19)
microsoft/windows_10
microsoft/windows_10 20h2
microsoft/windows_10 1607
microsoft/windows_10 1803
microsoft/windows_10 1809
microsoft/windows_10 1909
microsoft/windows_10 2004
microsoft/windows_7
microsoft/windows_8.1
microsoft/windows_rt_8.1
... and 9 more
Published Mar 11, 2021
Tracked Since Feb 18, 2026