CVE-2023-36767Network attack vector

Dangerous-extension filtering bypass via attachment preview

Published Sep 12, 2023 · Updated Oct 30, 2025

Security feature bypass in affected Microsoft Office releases allows remote attackers to evade Outlook filtering via a crafted attachment. When a user clicks the attachment Preview Pane, Outlook accepts an extension that its upload and download protection should block. Exploitation requires user interaction, and Microsoft states that this bypass alone has limited impact and must be chained with another flaw for an attack.

CVSS severity4.3
Medium
EPSS probability3.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Security feature bypass in affected Microsoft Office releases allows remote attackers to evade Outlook filtering via a crafted attachment. When a user clicks the attachment Preview Pane, Outlook accepts an extension that its upload and download protection should block. Exploitation requires user interaction, and Microsoft states that this bypass alone has limited impact and must be chained with another flaw for an attack.

The record

CVE
CVE-2023-36767
Published
Sep 12, 2023
Updated
Oct 30, 2025
Vendor
Microsoft
Product
Microsoft Office 2016
Classifications
CWE-20, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 12, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 30, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=16.0.0 <16.0.5413.1000

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Microsoft Office 2016version=16.0.0 <16.0.5413.1000
Microsoft · Microsoft Office 2019version=19.0.0 <https://aka.ms/OfficeSecurityReleases
Microsoft · Microsoft Office LTSC for Mac 2021version=16.0.1 <16.77.23091003
Microsoft · Microsoft Office 2013version=15.0.0 <15.0.5589.1000
Microsoft · Microsoft Office 2019 for Macversion=16.0.0 <16.77.23091003
Microsoft · Microsoft Office LTSC 2021version=16.0.1 <https://aka.ms/OfficeSecurityReleases
Microsoft · Microsoft 365 Apps for enterpriseversion=16.0.1 <https://aka.ms/OfficeSecurityReleases

Published CVSS scores

4.3Microsoft CorporationCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
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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