Local code execution via undisclosed heap overflow
Published May 12, 2026 · Updated May 12, 2026
Heap-based buffer overflow in Microsoft Office allows local users to execute code without authentication or user interaction. Microsoft has not published the affected Office component, the malformed input, or the memory-copy operation that overruns the heap buffer. Successful exploitation runs attacker-controlled code in the affected application's security context across the listed Windows, macOS, and Android editions.
Summary
What happened
Heap-based buffer overflow in Microsoft Office allows local users to execute code without authentication or user interaction. Microsoft has not published the affected Office component, the malformed input, or the memory-copy operation that overruns the heap buffer. Successful exploitation runs attacker-controlled code in the affected application's security context across the listed Windows, macOS, and Android editions.
The record
- CVE
- CVE-2026-40363
- Published
- May 12, 2026
- Updated
- May 12, 2026
- Vendor
- Microsoft
- Product
- Microsoft Office LTSC for Mac 2024
- Classifications
- CWE-122, T1203
- Attack vector
- local
- 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=16.0.0 <16.109.26051019
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.
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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