Local privilege escalation via clipboard use-after-free
Published Jan 13, 2026 · Updated Jan 13, 2026
Use after free in Microsoft Windows Clipboard Server allows local users on affected Windows releases to elevate privileges through a race. Microsoft has not disclosed the specific function or object whose lifetime is mishandled; the published mechanism is concurrent access to freed memory. Exploitation requires local access and winning a high-complexity race, needs no prior privileges or user interaction, and grants elevated control.
Summary
What happened
Use after free in Microsoft Windows Clipboard Server allows local users on affected Windows releases to elevate privileges through a race. Microsoft has not disclosed the specific function or object whose lifetime is mishandled; the published mechanism is concurrent access to freed memory. Exploitation requires local access and winning a high-complexity race, needs no prior privileges or user interaction, and grants elevated control.
The record
- CVE
- CVE-2026-20844
- Published
- Jan 13, 2026
- Updated
- Jan 13, 2026
- Vendor
- Microsoft
- Product
- Windows Server 2019
- Classifications
- CWE-416, CWE-362, T1068
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 13, 2026CVE publishedPublication date reported by the CVE source.
- Jan 13, 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=10.0.17763.0 <10.0.17763.8276
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
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.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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