Code execution via use-after-free
Published Jan 13, 2026 · Updated Jan 13, 2026
Use-after-free in Microsoft Office Excel allows attackers to execute code locally after a user opens a crafted workbook. Microsoft identifies the memory-lifetime error but has not disclosed the affected function, freed object, or workbook record that triggers reuse. Exploitation requires user interaction and runs code in the user's context; no prior privilege or network access is required.
Summary
What happened
Use-after-free in Microsoft Office Excel allows attackers to execute code locally after a user opens a crafted workbook. Microsoft identifies the memory-lifetime error but has not disclosed the affected function, freed object, or workbook record that triggers reuse. Exploitation requires user interaction and runs code in the user's context; no prior privilege or network access is required.
The record
- CVE
- CVE-2026-20950
- Published
- Jan 13, 2026
- Updated
- Jan 13, 2026
- Vendor
- Microsoft
- Product
- Microsoft Office LTSC for Mac 2024
- Classifications
- CWE-416, T1203
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 13, 2026CVE publishedPublication date reported by the CVE source.
- Jan 13, 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 <16.105.26011018
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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