CVE-2026-44818
HIGH 7Integer underflow (wrap or wraparound) in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
ELEVATED IMPACT
Severe if exploited (CVSS 7), but no known exploitation and low modeled probability. Patch on a normal cadence.
Exploitation likelihood
0.3%chance of exploitation in 30 days · 18th percentile
○ In CISA KEV
○ Public exploit / PoC
Impact if exploited
7CVSS 3.1 · HIGH
- ConfidentialityHigh
- IntegrityHigh
- AvailabilityHigh
What an attacker needs
- ⚠Access: Requires local access to the host
- ✓Privileges: No account or privileges required
- ⚠User interaction: A user must take an action (click / open a file)
- ⚠Complexity: Needs a race window or specific setup
✓ lowers the bar for an attacker · ⚠ raises it
Affected
Vendors Microsoft
Products Microsoft 365 Apps For Enterprise Microsoft Excel 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
Weakness (CWE)
- CWE-362: Race condition
CVSS vector
CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C