CVE-2026-55039

HIGH

Integer underflow (wrap or wraparound) in Microsoft Office Excel allows an unauthorized attacker to execute code locally.

CVSS v3.1 Score

7.8
HIGH
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Attack Vector
LOCAL
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Published: 7/14/2026Modified: 7/16/2026

Related Intelligence (1)

CRITICALZero Day

Patch Tuesday - July 2026

Microsoft is publishing 622 vulnerabilities on July 2026 Patch Tuesday , including a record-breaking 416 Windows vulnerabilities. Microsoft is aware of exploitation in the wild for two of the vulnerabilities published today, both of which are listed on CISA KEV, as well as public disclosure for one other. As usual, browser vulns are not included in the Patch Tuesday count above. Rapid7 noted last

CVE-2026-55040CVE-2026-56164
Rapid7

References (1)

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55039PatchVendor Advisory