CVE-2026-45459

User-assisted security-feature bypass

Published Jun 9, 2026 · Updated Jun 9, 2026

Protection mechanism failure in Microsoft Excel allows attackers to bypass a security feature after a user opens a crafted file locally. Microsoft identifies the affected component only as Excel and has not disclosed which protection processes the untrusted workbook content incorrectly. Exploitation requires user interaction on an affected Windows or macOS Office client and causes limited information disclosure, with no reported integrity or availability impact.

CVSS severity3.3
Low
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Protection mechanism failure in Microsoft Excel allows attackers to bypass a security feature after a user opens a crafted file locally. Microsoft identifies the affected component only as Excel and has not disclosed which protection processes the untrusted workbook content incorrectly. Exploitation requires user interaction on an affected Windows or macOS Office client and causes limited information disclosure, with no reported integrity or availability impact.

The record

CVE
CVE-2026-45459
Published
Jun 9, 2026
Updated
Jun 9, 2026
Vendor
Microsoft
Product
Microsoft Office LTSC for Mac 2024
Classifications
CWE-693, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=-

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Microsoft · Microsoft Office LTSC for Mac 2024version=-
Microsoft · Microsoft Office LTSC for Mac 2021version=-
Microsoft · Microsoft Office 365 for Macversion=-
Microsoft · Microsoft Office LTSC 2024version=16.0.0 <https://aka.ms/OfficeSecurityReleases
Microsoft · Microsoft 365 Apps for enterpriseversion=16.0.1 <https://aka.ms/OfficeSecurityReleases

Published CVSS scores

3.3Microsoft CorporationCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-693Protection Mechanism Failure
T1204.002User Execution: Malicious File

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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