May 2026: Microsoft Word Remote Code Execution Vulnerability
CVE-2026-40364 Published on May 12, 2026
Microsoft Word Remote Code Execution Vulnerability
Access of resource using incompatible type ('type confusion') in Microsoft Office Word allows an unauthorized attacker to execute code locally.
Weakness Types
What is an Object Type Confusion Vulnerability?
The program allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.
CVE-2026-40364 has been classified to as an Object Type Confusion vulnerability or weakness.
Use of Uninitialized Resource
The software uses or accesses a resource that has not been initialized. When a resource has not been properly initialized, the software may behave unexpectedly. This may lead to a crash or invalid memory access, but the consequences vary depending on the type of resource and how it is used within the software.
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-2026-40364
Want to know whenever a new CVE is published for Microsoft products? stack.watch will email you.
Affected Versions
Microsoft 365 Apps for Enterprise:- Version 16.0.1 and below https://aka.ms/OfficeSecurityReleases is affected.
- Version 19.0.0 and below https://aka.ms/OfficeSecurityReleases is affected.
- Version 16.0.1 and below https://aka.ms/OfficeSecurityReleases is affected.
- Version 16.0.0 and below https://aka.ms/OfficeSecurityReleases is affected.
- Version 16.0.1 and below 16.109.26051019 is affected.
- Version 16.0.0 and below 16.109.26051019 is affected.
- Version 16.0.1 and below 16.0.5552.1000 is affected.