All vulnerabilities
CVE-2023-23397

Microsoft Office Outlook Privilege Escalation Vulnerability

Microsoft OfficeApplications & CMS
Open in ThreatlineRecord JSON
CVSS
9.8Critical
ExploitationExploited in the wildAdded to KEV 14 Mar 2023CISA KEV
Exploit odds (EPSS)97.2%Chance of exploitation activity in the next 30 days, higher than 99% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in16.0.5387.1000Also 15.0.5537.1000CVE List
Federal deadline4 Apr 2023Remediation due date for US federal agenciesCISA KEV
CISA required actionApply updates per vendor instructions. CISA KEV

What fixes it

  • 16.0.5387.1000Microsoft Outlook 2016CVE List
  • 15.0.5537.1000Microsoft Outlook 2013 Service Pack 1CVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Timeline

  1. 14 Mar 2023Added to CISA KEVCISA KEV
  2. 14 Mar 2023, 16:55 UTCPublishedCVE List

Reports 1

1 outlet mention it. Reports are not confirmation; each links to its source.

Description

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

Text from CVE List

Affected versions 5

  • Microsoft Office LTSC 2021affected: 16.0.1 before https://aka.ms/OfficeSecurityReleasesCVE List
  • Microsoft Outlook 2016affected: 16.0.0.0 before 16.0.5387.1000CVE List
  • Microsoft 365 Apps for Enterpriseaffected: 16.0.1 before https://aka.ms/OfficeSecurityReleasesCVE List
  • Microsoft Office 2019affected: 19.0.0 before https://aka.ms/OfficeSecurityReleasesCVE List
  • Microsoft Outlook 2013 Service Pack 1affected: 15.0.0.0 before 15.0.5537.1000CVE List

References 4