Code execution via undisclosed integer underflow
Published Aug 11, 2026 · Updated Aug 25, 2026
Integer underflow in affected Microsoft Office desktop editions allows local users to execute code after attacker-controlled interaction. Microsoft identifies related heap overflow and out-of-bounds read conditions but does not disclose the affected component or erroneous arithmetic operation. Successful exploitation requires user interaction and executes code in the affected user's local security context.
Summary
What happened
Integer underflow in affected Microsoft Office desktop editions allows local users to execute code after attacker-controlled interaction. Microsoft identifies related heap overflow and out-of-bounds read conditions but does not disclose the affected component or erroneous arithmetic operation. Successful exploitation requires user interaction and executes code in the affected user's local security context.
The record
- CVE
- CVE-2026-64909
- Published
- Aug 11, 2026
- Updated
- Aug 25, 2026
- Vendor
- Microsoft
- Product
- Microsoft Office LTSC for Mac 2024
- Classifications
- CWE-122, CWE-191, CWE-125, T1203
- Attack vector
- local
- Privileges
- unauthenticated
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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=16.0.0 <16.112.26081010
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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