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Weekly Signal
Live intelligence Updated 20 Aug 2026 · 01:51 UTC

Microsoft · 365 Apps, Office, Office Long Term Servicing Channel +1 more

CVE-2023-23397

Microsoft Office Outlook Privilege Escalation Vulnerability

Recommended action

Treat this as an immediate remediation priority. Apply updates per vendor instructions.

View response plan
CVSS9.8
EPSS97.4%
KEVYes
ExploitationConfirmed exploitation
PatchPatch or guidance available ↓

Assessment

Why it matters

CISA lists this vulnerability as known to be exploited; exploitation is confirmed; EPSS is 97.4%; technical severity is CVSS 9.8.

Microsoft Outlook Elevation of Privilege Vulnerability

Who should care

  • Teams operating 365 Apps, Office, Office Long Term Servicing Channel +1 more
  • Vulnerability and exposure management teams
  • Security operations teams monitoring exploitation activity

Response plan

What I would do

  1. Confirm whether 365 Apps, Office, Office Long Term Servicing Channel +1 more is present in the environment.
  2. Identify affected versions and establish whether vulnerable services are exposed or reachable.
  3. Apply updates per vendor instructions.
  4. Review relevant security telemetry for evidence of attempted or successful exploitation.
  5. Document the remediation decision and track it to verified completion.

Vendor remediation

Patch and remediation links

Use the vendor source below to confirm the correct fixed version, package or mitigation for your affected product.

Technical details

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE
CWE-294
Affected versions
Microsoft 365 Apps (Version: -); Microsoft Office (Version: 2019); Microsoft Office Long Term Servicing Channel (Version: 2021); Microsoft Outlook (Version: 2016)
Published
14 March 2023
Attack vector
Network
Privileges required
None
User interaction
None

Signal timeline

  1. CVE published
  2. Added to CISA KEV
  3. Latest EPSS score: 97.4%
  4. Signal calculated at 85

External references

Live public intelligence This assessment combines public-source evidence. Validate the affected product, version and exposure against your own environment before making a risk decision.