Vulnerability report

Exploitation Attempts Observed in the Wild Confirmed Confidence In CISA KEV

CVE-2023-23397

Microsoft Outlook Elevation of Privilege Vulnerability

Microsoft Office LTSC 2021 · affected before https://aka.ms/OfficeSecurityReleases

Watch CVE-2023-23397 Browse KEV feed
Severity
CVSS 9.8 · Critical
Confidence
Confirmed
Exploit status
Exploitation Attempts Observed in the Wild
EPSS
97.2%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2023-23397 is an unauthenticated Microsoft Outlook Elevation of Privilege Vulnerability.

Have exploitation attempts been observed?

Yes. Exploitation attempts have been reported for this vulnerability. Previdian lists it as a known exploited vulnerability. Listed in CISA KEV. Also reported by third-party sources. Confidence is confirmed.

Who is affected?

Microsoft Office LTSC 2021 affected before https://aka.ms/officesecurityreleases.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

Microsoft Outlook Elevation of Privilege Vulnerability

Microsoft Outlook Elevation of Privilege Vulnerability

Microsoft Affected
Microsoft Office LTSC 2021
Before https://aka.ms/OfficeSecurityReleases
Microsoft Affected
Microsoft Outlook 2016
Before 16.0.5387.1000
Microsoft Affected
Microsoft 365 Apps for Enterprise
Before https://aka.ms/OfficeSecurityReleases
Microsoft Affected
Microsoft Office 2019
Before https://aka.ms/OfficeSecurityReleases
Microsoft Affected
Microsoft Outlook 2013 Service Pack 1
Before 15.0.5537.1000
View vendor advisory (opens in new tab)
Published
14 Mar 2023
Exploitation Attempts Reported
14 Mar 2023
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

microsoft cisa nessus_scanner

CVE References

Exploitation evidence

Evidence of exploitation attempts

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploitation Attempts Observed in the Wild

CISA

Recorded 14 Mar 2023

A trusted third party reported exploitation attempts.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
CISA First 2023-03-14 00:00 UTC
Tenable Blog 2026-06-02 14:20 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Scanner Artifacts

Scanner and exploit-framework references linked to this CVE.

Scanner Reference Detected
Nessus https://www.tenable.com/plugins/nessus/172607 02 Jun 2025

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

9.8 Critical

Potential damage if exploited. Separate from whether attackers are using it.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

97.2%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Improper Input Validation CWE-20

Recent mention · Tenable Blog

Inside the customer environment: Where threat actors, vulnerabilities, and exposed assets intersect

Tenable Research has developed a graph-based model linking 600+ threat groups to real-world customer exposures. It reveals which vulnerabilities sit at the intersection of severity, active exploitation, and organizational risk.Key takeawaysThe "patch everything" strategy is...

Read full advisory

Timeline

From disclosure to observed exploitation attempts

  1. 14:20 UTC

    KEV confirmed by Tenable Blog

    Exploitation attempts reported by an external source

  2. 09:27 UTC

    Nessus plugin available

    Scanner coverage available

  3. 16:55 UTC

    CVE published

    Vulnerability disclosed publicly

  4. 00:00 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  5. 22:08 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

Start 14-day Pro trial Read API docs
  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2023-23397

Sample API response 
{
  "cve_id": "CVE-2023-23397",
  "confidence": "Confirmed",
  "cvss_score": 9.8,
  "cvss_estimated": false,
  "epss_score": 0.97159,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}