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CVE-2023-23397

Microsoft Office Outlook Privilege Escalation

9.8 CRITICALActively exploited (CISA KEV)EPSS 97.2%
  1. Published14 Mar 2023
  2. Added to CISA KEV14 Mar 2023
  3. Remediation due4 Apr 2023
Actively exploited (CISA KEV)

Microsoft Office Outlook contains a privilege escalation vulnerability that allows for a NTLM Relay attack against another service to authenticate as the user.

Added to KEV: 14 Mar 2023Federal remediation due: 4 Apr 2023

Description

Microsoft Outlook Elevation of Privilege Vulnerability

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Microsoft 365 Appsall versions
Microsoft Office2019
Microsoft Office Long Term Servicing Channel2021
Microsoft Outlook2013 · 2016

Remediation

No fixed version is recorded in the NVD data. Check the vendor advisory for the latest guidance.

References

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Frequently asked

Is CVE-2023-23397 being actively exploited?

Yes. CVE-2023-23397 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 14 Mar 2023.

How severe is CVE-2023-23397?

CVE-2023-23397 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 97.2% probability of exploitation.

Which products are affected by CVE-2023-23397?

Affected products include Microsoft 365 Apps, Microsoft Office, Microsoft Office Long Term Servicing Channel, Microsoft Outlook.

How do I fix CVE-2023-23397?

Apply the vendor's patch or advisory guidance, then verify no affected versions remain across your devices.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2023-23397 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, a risk for it never ranks below high, and the update that fixes it moves to the Emergency patch lane. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.