CVE-2023-23397
CriticalExploitedPublic exploitMicrosoft Outlook Elevation of Privilege Vulnerability
Published Nov 29, 2023 · Updated Oct 21, 2025 · Also known as TR-23-0156, TR-23-0603
Key Facts
Patch immediately- CVE-2023-23397 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting 365 Apps (Microsoft), Office (Microsoft), Office Long Term Servicing Channel (Microsoft) and 6 more products.
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Mar 14, 2023 and is known to be used in ransomware campaigns. Public exploit code is available.
- EPSS estimates a 97% probability of exploitation in the next 30 days.
- Fixed versions are available, including Microsoft 365 Apps for Enterprise https://aka.ms/OfficeSecurityReleases, Microsoft Office 2019 https://aka.ms/OfficeSecurityReleases, Microsoft Office LTSC 2021 https://aka.ms/OfficeSecurityReleases.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
97%
Higher than 99.8% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings, used by ransomware
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2023-23397 brief as a PDF
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Description
Microsoft Outlook Elevation of Privilege Vulnerability
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Mar 14, 2023 | Apr 4, 2023 | Not reported |
| Industry KEV feed | Mar 14, 2023 | Apr 4, 2023 | Known |
| CIRCL KEV | Mar 14, 2023 | Apr 4, 2023 | Not reported |
| ENISA EUVD | Mar 14, 2023 | n/a | Not reported |
Required action: Apply updates per vendor instructions.
Affected Products
11 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| 365 AppsMicrosoft | See advisory | n/a |
| OfficeMicrosoft | 2019 | n/a |
| Office Long Term Servicing ChannelMicrosoft | 2021 | n/a |
| OutlookMicrosoft | 2013-sp1, 2016 | n/a |
| Microsoft 365 Apps for Enterprise | >= 16.0.1 | https://aka.ms/OfficeSecurityReleases |
Patched Releases
Microsoft 365 Apps for Enterprise
https://aka.ms/OfficeSecurityReleases
Microsoft Office 2019
https://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC 2021
https://aka.ms/OfficeSecurityReleases
Microsoft Outlook 2013 Service Pack 1
15.0.5537.1000
Microsoft Outlook 2016
16.0.5387.1000
Timeline
Added to CISA KEV
Mar 14, 2023
Added to Industry KEV feed
Mar 14, 2023
Added to CIRCL KEV
Mar 14, 2023
Added to ENISA EUVD
Mar 14, 2023
Publicly disclosed
Nov 29, 2023
Last updated
Oct 21, 2025
Weakness Type
- CWE-20 Improper Input Validation
- CWE-294 Authentication Bypass by Capture-replay
References
- advisoryhttps://chromereleases.googleblog.com/2023/11/stable-channel-update-for-desktop_28.html
- advisoryhttps://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-0872
- advisoryhttps://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-0878
- advisoryhttps://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-20463
- advisoryhttps://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-20471
FAQ
Common Questions.
Microsoft Outlook Elevation of Privilege Vulnerability
Affected: 365 Apps (Microsoft); Office (Microsoft) versions 2019; Office Long Term Servicing Channel (Microsoft) versions 2021, among others. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Mar 14, 2023 and is known to be used in ransomware campaigns.
Yes. It was added on Mar 14, 2023 with a federal remediation due date of Apr 4, 2023.
Public exploit code is available.
Fixed versions are available, including Microsoft 365 Apps for Enterprise https://aka.ms/OfficeSecurityReleases, Microsoft Office 2019 https://aka.ms/OfficeSecurityReleases, Microsoft Office LTSC 2021 https://aka.ms/OfficeSecurityReleases.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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