Microsoft Excel, Office and 365 fix a high-severity vulnerability

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[TLP:CLEAR] Microsoft Excel, Office and 365 fix a high-severity vulnerability

Microsoft fixes a high-severity vulnerability in MS Excel, Office and 365 [1]. The fix for MS Excel is in build 16.0.5561.1001 [1], and the fixed MS Office and 365 builds can be checked at [2].

Microsoft Excel, Office, 365 - RCE (CVE-2026-62870)

CVSS 8.8 (High)

An unauthenticated remote attacker can use social engineering to trick the victim into opening a specially crafted file and thereby execute code on the affected machine [1].

The vulnerability is present in product:

Microsoft Excel 2016; <16.0.5561.1001;

CVSS: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

More information:

CVE-2026-62870 at cve.org, NVD
CWE-416: Use After Free at cwe.mitre.org

The vulnerability was publicly disclosed 31. 7. 2026.

Links

By CESNET, z.s.p.o. Martin Krajči on 4. 8. 2026.

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[TLP:CLEAR] Microsoft Excel, Office and 365 fix a high-severity vulnerability

Microsoft Excel, Office, 365 - RCE (CVE-2026-62870)

CVSS 8.8 (High)

Links