Code execution via undisclosed heap buffer overflow
Published Jul 14, 2026 · Updated Jul 14, 2026
Heap-based buffer overflow in Microsoft Office Excel allows attackers to execute code locally after a user opens a crafted file. Microsoft has not disclosed the affected Excel parser or the specific operation that overruns a heap allocation while processing untrusted workbook content. Opening attacker-supplied content is required, and successful exploitation runs code in the context of the affected user.
Summary
What happened
Heap-based buffer overflow in Microsoft Office Excel allows attackers to execute code locally after a user opens a crafted file. Microsoft has not disclosed the affected Excel parser or the specific operation that overruns a heap allocation while processing untrusted workbook content. Opening attacker-supplied content is required, and successful exploitation runs code in the context of the affected user.
The record
- CVE
- CVE-2026-55053
- Published
- Jul 14, 2026
- Updated
- Jul 14, 2026
- Vendor
- Microsoft
- Product
- Microsoft Office LTSC for Mac 2024
- Classifications
- CWE-122, T1203, T1204.002
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 14, 2026CVE publishedPublication date reported by the CVE source.
- Jul 14, 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 <16.111.26071215
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.
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Technologies
Your stack
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Your stack
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