SYSTEM privilege escalation via fdwsd.dll race condition
Published Jun 9, 2026 · Updated Jun 9, 2026
A race condition in fdwsd.dll in Microsoft Windows allows local users with low privileges to elevate to SYSTEM through local execution. Function Discovery Service concurrently accesses a shared resource without proper synchronization, creating a use-after-free condition in fdwsd.dll. Exploitation requires local low-privileged access and a timing condition; successful exploitation grants SYSTEM-level control of the host.
Summary
What happened
A race condition in fdwsd.dll in Microsoft Windows allows local users with low privileges to elevate to SYSTEM through local execution. Function Discovery Service concurrently accesses a shared resource without proper synchronization, creating a use-after-free condition in fdwsd.dll. Exploitation requires local low-privileged access and a timing condition; successful exploitation grants SYSTEM-level control of the host.
The record
- CVE
- CVE-2026-42836
- Published
- Jun 9, 2026
- Updated
- Jun 9, 2026
- Vendor
- Microsoft
- Product
- Windows Server 2019
- Classifications
- CWE-416, CWE-362, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jun 9, 2026CVE publishedPublication date reported by the CVE source.
- Jun 9, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=10.0.17763.0 <10.0.17763.8880
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
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo