CVEvulnerability
CVE-2021-26887
7.8 HIGH
Official page ↗
- Status
- Modified
- Published
- 2021-03-11
- Last modified
- 2026-08-19
- Assigner
- [email protected]
- CVSS 3.1 ([email protected])
- 7.8 HIGH — CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CVSS 3.1 ([email protected])
- 7.8 HIGH — CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CVSS 2.0 ([email protected])
- 4.6 MEDIUM — AV:L/AC:L/Au:N/C:P/I:P/A:P
- Weaknesses
- CWE-59
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.
Affected configurations
• 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
• microsoft windows server 2008
• microsoft windows server 2008 r2
• microsoft windows server 2012
• microsoft windows server 2012 r2
• microsoft windows server 2016
• microsoft windows server 2016 20h2
• microsoft windows server 2016 1909
• microsoft windows server 2016 2004
• microsoft windows server 2019
Related
Weakness · CWE (1)
- CWE-59 Improper Link Resolution Before File Access weakness
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-26887 msrc.microsoft.com
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26887 Patch, Vendor Advisory