CVE-2026-21259
Analyzed
Analyzed - Analysis Complete
Heap-Based Buffer Overflow in Excel Enables Local Privilege Escalation
Publication date: 2026-02-10
Last updated on: 2026-02-11
Assigner: Microsoft Corporation
Description
Description
Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to elevate privileges locally.
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| microsoft | 365_apps | * |
| microsoft | 365_apps | * |
| microsoft | excel | 2016 |
| microsoft | excel | 2016 |
| microsoft | office | 2019 |
| microsoft | office | 2019 |
| microsoft | office_long_term_servicing_channel | 2021 |
| microsoft | office_long_term_servicing_channel | 2021 |
| microsoft | office_long_term_servicing_channel | 2024 |
| microsoft | office_long_term_servicing_channel | 2024 |
| microsoft | office_online_server | to 16.0.10417.20097 (exc) |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-122 | A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). |
| CWE-787 | The product writes data past the end, or before the beginning, of the intended buffer. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability is a heap-based buffer overflow in Microsoft Office Excel. It allows an unauthorized attacker to elevate their privileges locally on the affected system.
How can this vulnerability impact me? :
The impact of this vulnerability is that an attacker can gain higher privileges on the local system without authorization. This means they could potentially execute actions or access data that normally require elevated permissions.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
I don't know
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