CVE-2021-26887
No exploitation reported by the sources we read.
- Published2021-03-11
- WeaknessCWE-59
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
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.
Timeline
dates in UTC- 2021-03-1116:15CVE publishedNVD
Observed activity
isMalicious corpus · updated 2026-10-23 18:48 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-26887?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-26887?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
NVD| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| — | all versions | no fix published | NVD |
| 20.x | = 20h2 | no fix published | NVD |
| 1607.x | = 1607 | no fix published | NVD |
| 1803.x | = 1803 | no fix published | NVD |
| 1809.x | = 1809 | no fix published | NVD |
| 1909.x | = 1909 | no fix published | NVD |
| 2004.x | = 2004 | no fix published | NVD |
| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| — | all versions | no fix published | NVD |
| 20.x | = 20h2 | no fix published | NVD |
| 1909.x | = 1909 | no fix published | NVD |
| 2004.x | = 2004 | no fix published | NVD |
| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| — | all versions | no fix published | NVD |
| — | = r2 | no fix published | NVD |
5 more products in the sources.
as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.
Fix
Advisories and patches
- portal.msrc.microsoft.comPatch · Vendor Advisory
Detection
- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- none listed PoC-in-GitHub
Sources
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Published
- 2021-03-11
- Last Modified
- 2026-08-19
- NVD status
- Modified
Frequently asked questions
What is CVE-2021-26887?
Is CVE-2021-26887 actively exploited?
What is the CVSS score for CVE-2021-26887?
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