Cyber Resilience

CVE-2021-26887

High

Published: 11 March 2021

Published
11 March 2021
Modified
24 February 2026
KEV Added
Patch
CVSS Score v3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.0034 57.0th percentile
Risk Priority 16 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-26887 is a high-severity Link Following (CWE-59) vulnerability in Microsoft Windows 10. Its CVSS base score is 7.8 (High).

Operationally, ranked in the top 43.0% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

<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…

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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>

CWE(s)

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

microsoft
windows 10
1607, 1803, 1809, 1909, 2004
microsoft
windows 7
all versions
microsoft
windows 8.1
all versions
microsoft
windows rt 8.1
all versions
microsoft
windows server 2008
all versions, r2
microsoft
windows server 2012
all versions, r2
microsoft
windows server 2016
1909, 2004, 20h2, all versions
microsoft
windows server 2019
all versions

Mitigating Controls

No mitigating controls mapped yet. The per-CVE control annotator has not reached this CVE.

References