Code execution via undisclosed integer underflow
Published Jun 9, 2026 · Updated Jun 9, 2026
Integer underflow in Microsoft Excel across affected Office clients and Office Online Server allows attackers to execute code via a crafted file. Microsoft identifies integer wraparound and a resulting heap-based buffer overflow, but has not disclosed the parser, file structure, or arithmetic operation involved. Exploitation requires a user to open the crafted file and runs code in that user's security context; no public exploitation is reported.
Summary
What happened
Integer underflow in Microsoft Excel across affected Office clients and Office Online Server allows attackers to execute code via a crafted file. Microsoft identifies integer wraparound and a resulting heap-based buffer overflow, but has not disclosed the parser, file structure, or arithmetic operation involved. Exploitation requires a user to open the crafted file and runs code in that user's security context; no public exploitation is reported.
The record
- CVE
- CVE-2026-45469
- Published
- Jun 9, 2026
- Updated
- Jun 9, 2026
- Vendor
- Microsoft
- Product
- Microsoft Office LTSC for Mac 2024
- Classifications
- CWE-191, CWE-122, T1203, T1204.002
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 9, 2026CVE publishedPublication date reported by the CVE source.
- Jun 9, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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- Affected versionversion=-
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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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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