Vulnerability · Published Mar 11, 2021 · Assigned by microsoft
CVE-2021-26887Microsoft Windows Folder Redirection Elevation of Privilege Vulnerability
High 7.8
In plain English
A high-severity security flaw in Windows 10 Version 1507 from Microsoft. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.1% (higher than 65% of all known vulnerabilities).
Official 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 products (as reported)
References
- Microsoft Windows Folder Redirection Elevation of Privilege Vulnerability vendor-advisory, patch
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26887 x_refsource_MISC, x_transferred