CVE-2026-44803: microsoft excel Integer Overflow or Wraparound

Vulnerability summary

CVE-2026-44803 is a high (CVSS 7.8) Integer Overflow or Wraparound vulnerability in microsoft excel. EPSS estimates a 0.47% chance of exploitation in the next 30 days, higher than 39% of scored vulnerabilities.

Timeline

1. 09-06-2026
   PublishedVulnerability first disclosed.
2. 24-09-2026
   Last modifiedVulnerability information updated.

Description

Integer overflow or wraparound in Windows Win32K - GRFX allows an unauthorized attacker to execute code locally.

• 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.