High severity · published May 12, 2026
CVE-2026-40358
Microsoft Office Remote Code Execution Vulnerability
8.4
CVSS
0.4%
EPSS
No
On KEV
Description
Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 31% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
OF
Office · Microsoft
2016; 2016; 2019; 2019 · source: NVD
M3
Microsoft 365 Apps for Enterprise · Microsoft
16.0.1 before https://aka.ms/OfficeSecurityReleases · source: vendor
MO
Microsoft Office 2016 · Microsoft
16.0.0 before 16.0.5552.1000 · source: vendor
MO
Microsoft Office 2019 · Microsoft
19.0.0 before https://aka.ms/OfficeSecurityReleases · source: vendor
MO
Microsoft Office LTSC 2021 · Microsoft
16.0.1 before https://aka.ms/OfficeSecurityReleases · source: vendor
MO
Microsoft Office LTSC 2024 · Microsoft
16.0.0 before https://aka.ms/OfficeSecurityReleases · source: vendor
MO
Microsoft Office LTSC for Mac 2021 · Microsoft
16.0.1 before 16.109.26051019 · source: vendor
MO
Microsoft Office LTSC for Mac 2024 · Microsoft
16.0.0 before 16.109.26051019 · source: vendor
OL
Office Long Term Servicing Channel · Microsoft
2021; 2021; 2021; 2024; 2024; 2024 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-40358
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-40358
Vendor Advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40358
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