CVE-2026-88186: microsoft 365_apps Heap-based Buffer Overflow

Vulnerability summary

CVE-2026-88186 is a high (CVSS 8.8) Heap-based Buffer Overflow vulnerability in microsoft 365_apps. EPSS estimates a 0.72% chance of exploitation in the next 30 days, higher than 53.1% of scored vulnerabilities.

Timeline

1. 13-10-2026
   PublishedVulnerability first disclosed.
2. 16-10-2026
   Last modifiedVulnerability information updated.

Description

Heap-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute code over a network.

• CWE-122Heap-based Buffer OverflowA 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-190Integer Overflow or WraparoundThe product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.