Unauthenticated code execution via freed completion object
Published Jul 8, 2025 · Updated Feb 26, 2026
Use-after-free in Microsoft Windows KDC Proxy Service on affected Windows Server releases allows remote attackers to execute code via network requests. The KpsSocketIoCompletion routine permits an asynchronous socket-completion object to be used after its lifetime ends. Exploitation requires a high-complexity timing condition but no authentication or user interaction, and successful code execution can fully compromise the server.
Summary
What happened
Use-after-free in Microsoft Windows KDC Proxy Service on affected Windows Server releases allows remote attackers to execute code via network requests. The KpsSocketIoCompletion routine permits an asynchronous socket-completion object to be used after its lifetime ends. Exploitation requires a high-complexity timing condition but no authentication or user interaction, and successful code execution can fully compromise the server.
The record
- CVE
- CVE-2025-49735
- Published
- Jul 8, 2025
- Updated
- Feb 26, 2026
- Vendor
- Microsoft
- Product
- Windows Server 2019
- Classifications
- CWE-416, T1210
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 8, 2025CVE publishedPublication date reported by the CVE source.
- Feb 26, 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 <10.0.17763.7434
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.
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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