Local privilege escalation via heap buffer overflow
Published May 12, 2026 · Updated May 12, 2026
Heap-based buffer overflow in Microsoft Windows Remote Desktop Services allows local users with low privileges to elevate privileges. Microsoft has not disclosed the affected function, buffer, input path, or unchecked copy or length operation that overwrites heap memory. A local low-privileged account is required; successful exploitation compromises data and service operation in a higher-privilege context.
Summary
What happened
Heap-based buffer overflow in Microsoft Windows Remote Desktop Services allows local users with low privileges to elevate privileges. Microsoft has not disclosed the affected function, buffer, input path, or unchecked copy or length operation that overwrites heap memory. A local low-privileged account is required; successful exploitation compromises data and service operation in a higher-privilege context.
The record
- CVE
- CVE-2026-40398
- Published
- May 12, 2026
- Updated
- May 12, 2026
- Vendor
- Microsoft
- Product
- Windows Server 2019
- Classifications
- CWE-122, T1068
- Attack vector
- local
- Privileges
- authenticated
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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