Aug 2026: Microsoft Office Remote Code Execution Vulnerability
CVE-2026-64909 Published on August 11, 2026

Microsoft Office Remote Code Execution Vulnerability
Integer underflow (wrap or wraparound) in Microsoft Office allows an unauthorized attacker to execute code locally.

Vendor Advisory NVD

Weakness Types

What is an Integer underflow Vulnerability?

The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result. This can happen in signed and unsigned cases.

CVE-2026-64909 has been classified to as an Integer underflow vulnerability or weakness.

Out-of-bounds Read

The software reads data past the end, or before the beginning, of the intended buffer. Typically, this can allow attackers to read sensitive information from other memory locations or cause a crash. A crash can occur when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string. The expected sentinel might not be located in the out-of-bounds memory, causing excessive data to be read, leading to a segmentation fault or a buffer overflow. The software may modify an index or perform pointer arithmetic that references a memory location that is outside of the boundaries of the buffer. A subsequent read operation then produces undefined or unexpected results.

Heap-based Buffer Overflow

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().


Products Associated with CVE-2026-64909

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Microsoft Office 365
 
Microsoft Office 2019
 
Microsoft 365 Apps
 
Microsoft Office Macos 2021
 
Microsoft Office 2021
 
Microsoft Office 2024
 
Microsoft Office Macos 2024
 
Microsoft Office 2016
 

Affected Versions

Microsoft 365 Apps for Enterprise: Microsoft Office 2016: Microsoft Office 2019: Microsoft Office 365 for Mac: Microsoft Office LTSC 2021: Microsoft Office LTSC 2024: Microsoft Office LTSC for Mac 2021: Microsoft Office LTSC for Mac 2024: