CISA KEV · Known exploitedHigh

CVE-2023-21529

Microsoft Exchange Server

CVE-2023-21529 affects Microsoft Exchange Server. Review the CVSS score, exploitation signals, affected versions, remediation status, and linked source material before making a change.

CVSS
8.8
EPSS
62.1%
99.1% percentile
CISA KEV
Listed
Published
2023.02.15
PRIORITY ASSESSMENT

Immediate review

CISA has listed this vulnerability in the Known Exploited Vulnerabilities catalog.

Known exploitationConfirmed by CISA KEV
Exploit probability62.1%
Technical severityCVSS 8.8

Vulnerability overview

CVE-2023-21529 affects Microsoft Exchange Server. Review the CVSS score, exploitation signals, affected versions, remediation status, and linked source material before making a change.

Affected product and versions

Product
Microsoft Exchange Server
Affected versions
15.02.0, 15.00.0, 15.01.0, 2013, 2016, 2019
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
CISA required action

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Due date: 2026.04.27
  1. 1
    Identify

    Confirm that Microsoft Exchange Server and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE
CWE-502
KEV added
2026.04.13
Ransomware use
확인됨
CVE-2023-21529 — Microsoft Exchange Server | SECUFOCUS NOW