CVE-2021-31949

Code execution via crafted file opening

Published Jun 8, 2021 · Updated Feb 28, 2025

Code injection in Microsoft Outlook in affected Office 2019, Outlook 2013/2016, and Microsoft 365 Apps builds allows attackers to execute code. Microsoft has not disclosed the affected parser, file format, or unsafe operation performed on the crafted file. Exploitation requires a user to open the file in Outlook; the Preview Pane alone is not an attack vector.

CVSS severity7.0
High
EPSS probability2.57%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code injection in Microsoft Outlook in affected Office 2019, Outlook 2013/2016, and Microsoft 365 Apps builds allows attackers to execute code. Microsoft has not disclosed the affected parser, file format, or unsafe operation performed on the crafted file. Exploitation requires a user to open the file in Outlook; the Preview Pane alone is not an attack vector.

The record

CVE
CVE-2021-31949
Published
Jun 8, 2021
Updated
Feb 28, 2025
Vendor
Microsoft
Product
Microsoft Office 2019
Classifications
CWE-94, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 8, 2021CVE publishedPublication date reported by the CVE source.
  2. Feb 28, 2025Record 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=19.0.0 <https://aka.ms/OfficeSecurityReleases

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Microsoft · Microsoft Office 2019version=19.0.0 <https://aka.ms/OfficeSecurityReleases
Microsoft · Microsoft Outlook 2016version=16.0.0.0 <16.0.5356.1000.
Microsoft · Microsoft Outlook 2013version=15.0.0.0 <15.0.5475.1000
Microsoft · Microsoft 365 Apps for enterpriseversion=16.0.1 <https://aka.ms/OfficeSecurityReleases

Published CVSS scores

7.8NISTCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.8NISTAV:N/AC:M/Au:N/C:P/I:P/A:P
7.0Microsoft CorporationCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-94Improper Control of Generation of Code ('Code Injection')
T1204.002Malicious 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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