Local file overwrite causing denial of service
Published Mar 11, 2021 · Updated Aug 19, 2026
User Profile Service in Microsoft Windows versions listed for CVE-2021-26886 allows local users to cause denial of service via a directory junction. The service follows an attacker-created junction and overwrites the contents of a chosen file instead of restricting the operation to the intended profile path. Local users need low-privilege code execution, and the consequence is system availability loss without reported confidentiality impact.
Summary
What happened
User Profile Service in Microsoft Windows versions listed for CVE-2021-26886 allows local users to cause denial of service via a directory junction. The service follows an attacker-created junction and overwrites the contents of a chosen file instead of restricting the operation to the intended profile path. Local users need low-privilege code execution, and the consequence is system availability loss without reported confidentiality impact.
The record
- CVE
- CVE-2021-26886
- Published
- Mar 11, 2021
- Updated
- Aug 19, 2026
- Vendor
- Microsoft
- Product
- Windows 10 Version 1507
- Classifications
- T1565.001
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Mar 11, 2021CVE publishedPublication date reported by the CVE source.
- Aug 19, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=10.0.10240.0 <10.0.10240.18874
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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