Unauthenticated information disclosure via use-after-free
Published May 12, 2026 · Updated May 12, 2026
Use-after-free in Microsoft Windows TCP/IP allows remote attackers to disclose information over a network without authentication. Microsoft has not disclosed the affected TCP/IP path, object, or packet pattern, so the precise invalid post-lifetime access remains unspecified. No user interaction is required, and the published assessment limits the consequence to information disclosure without data modification or service interruption.
Summary
What happened
Use-after-free in Microsoft Windows TCP/IP allows remote attackers to disclose information over a network without authentication. Microsoft has not disclosed the affected TCP/IP path, object, or packet pattern, so the precise invalid post-lifetime access remains unspecified. No user interaction is required, and the published assessment limits the consequence to information disclosure without data modification or service interruption.
The record
- CVE
- CVE-2026-40406
- Published
- May 12, 2026
- Updated
- May 12, 2026
- Vendor
- Microsoft
- Product
- Windows Server 2019
- Classifications
- CWE-416
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 12, 2026CVE publishedPublication date reported by the CVE source.
- May 12, 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 <10.0.17763.8755
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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