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CVE-2026-55048: Microsoft Excel Remote Code Execution Risk

CVE-2026-55048 · published 3 months ago

Summary

Microsoft Excel users are at risk of malicious code being executed on their computers without permission. This could happen if they open a specially crafted spreadsheet from an untrusted source. To protect yourself, make sure to only open files from trusted sources and keep your software up to date.

What to do

Update microsoft microsoft 365 apps for enterprise to version https://aka.ms/OfficeSecurityReleases or later.
Update microsoft microsoft excel 2016 to version 16.0.5561.1001 or later.
Update microsoft microsoft office 2019 to version https://aka.ms/OfficeSecurityReleases or later.
Update microsoft microsoft office 365 for mac to version 16.111.26071215 or later.
Update microsoft microsoft office ltsc 2021 to version https://aka.ms/OfficeSecurityReleases or later.
Update microsoft microsoft office ltsc 2024 to version https://aka.ms/OfficeSecurityReleases or later.
Update microsoft microsoft office ltsc for mac 2021 to version 16.111.26071215 or later.
Update microsoft microsoft office ltsc for mac 2024 to version 16.111.26071215 or later.
Update microsoft office online server to version 16.0.10417.20175 or later.
Update microsoft office_online_server to version 16.0.10417.20175 or later.

Affected software

Vendor	Product	Affected versions
microsoft	microsoft 365 apps for enterprise	< https://aka.ms/OfficeSecurityReleases 16.0.1
microsoft	microsoft excel 2016	< 16.0.5561.1001
microsoft	microsoft office 2019	< https://aka.ms/OfficeSecurityReleases 19.0.0
microsoft	microsoft office 365 for mac	< 16.111.26071215
microsoft	microsoft office ltsc 2021	< https://aka.ms/OfficeSecurityReleases 16.0.1
microsoft	microsoft office ltsc 2024	< https://aka.ms/OfficeSecurityReleases 16.0.0
microsoft	microsoft office ltsc for mac 2021	< 16.111.26071215
microsoft	microsoft office ltsc for mac 2024	< 16.111.26071215
microsoft	office online server	< 16.0.10417.20175
microsoft	365_apps	All versions `cpe:2.3:a:microsoft:365_apps:-::::enterprise::x64:*`
microsoft	excel	2016 `cpe:2.3:a:microsoft:excel:2016::::::x64:`
microsoft	microsoft_365	All versions `cpe:2.3:a:microsoft:microsoft_365:-:::::macos::`
microsoft	office_2019	All versions `cpe:2.3:a:microsoft:office_2019:-::::::x64:`
microsoft	office_2021	All versions `cpe:2.3:a:microsoft:office_2021:-::::ltsc:-:x64:`
microsoft	office_2024	All versions `cpe:2.3:a:microsoft:office_2024:-::::ltsc:-:x64:`
microsoft	office_online_server	< 16.0.10417.20175 `cpe:2.3:a:microsoft:office_online_server::::::::`

Original advisory text

Microsoft Excel Remote Code Execution Vulnerability

Integer overflow or wraparound in Microsoft Office Excel allows an unauthorized attacker to execute code locally.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55048 vendor-advisory patch

Fix within

Internet-facing 14 days

Internal At next upgrade

Not known to be exploited
Needs hands-on effort to exploit
Gives an attacker full control

Severity

7.8 High

Exploitation

<1% chance of attack within 30 days

Type

CWE-190Integer Overflow

CWE-122Heap-based Buffer Overflow

Timeline

Published14 Jul 2026

Updated4 Nov 2026

First seen14 Jul 2026

Sources

CVE-2026-55048 · NVD

CVE-2026-55048 · MITRE

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