Privilege escalation via heap-based overflow
Published Aug 11, 2026 · Updated Aug 25, 2026
Heap-based buffer overflow in Windows Key Guard in Microsoft Windows allows local authenticated attackers to elevate privileges. Microsoft has not published the affected function or code path; public records disclose only that Key Guard performs a heap write past an allocated buffer boundary. Successful exploitation requires local code execution with low privileges and can yield full control of the host, with no evidence in the reviewed records of remote reachability or public exploitation details.
Summary
What happened
Heap-based buffer overflow in Windows Key Guard in Microsoft Windows allows local authenticated attackers to elevate privileges. Microsoft has not published the affected function or code path; public records disclose only that Key Guard performs a heap write past an allocated buffer boundary. Successful exploitation requires local code execution with low privileges and can yield full control of the host, with no evidence in the reviewed records of remote reachability or public exploitation details.
The record
- CVE
- CVE-2026-66799
- Published
- Aug 11, 2026
- Updated
- Aug 25, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-122, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Aug 11, 2026CVE publishedPublication date reported by the CVE source.
- Aug 25, 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?
What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
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.
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Technologies
Your stack
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Your stack
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