CVE-2021-26887

Microsoft Windows Folder Redirection Elevation of Privilege Vulnerability

HIGH
7.8
CVSS Score
Published: March 11, 2021 at 03:42 PM UTC
Updated: August 19, 2026 at 05:35 PM UTC
18 products affected across 1 vendorWindows Server 2016Windows Server 2019Windows Server 2012

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Severity
HIGH7.8
Exploit prediction
EPSS 1%
SSVC
No known exploit

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>

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.8HIGHmicrosoft
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-59

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