Authenticated privilege escalation via SMB race condition
Published Jan 13, 2026 · Updated Jan 13, 2026
A race condition in Microsoft Windows SMB Server allows remote authenticated users to elevate privileges through network requests. Microsoft identifies improper synchronization of a shared resource but has not disclosed the responsible function, shared object, or conflicting SMB operations. Exploitation requires valid low-level privileges and winning a high-complexity race, after which elevated access can compromise the affected host.
Summary
What happened
A race condition in Microsoft Windows SMB Server allows remote authenticated users to elevate privileges through network requests. Microsoft identifies improper synchronization of a shared resource but has not disclosed the responsible function, shared object, or conflicting SMB operations. Exploitation requires valid low-level privileges and winning a high-complexity race, after which elevated access can compromise the affected host.
The record
- CVE
- CVE-2026-20848
- Published
- Jan 13, 2026
- Updated
- Jan 13, 2026
- Vendor
- Microsoft
- Product
- Windows Server 2019
- Classifications
- CWE-362, T1068
- Attack vector
- network
- Privileges
- authenticated
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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