CVE-2023-21529
Microsoft Exchange Server Remote Code Execution Vulnerability
- High 8.8
- Exploited: added to CISA KEV 13 Apr 2026
- Used in ransomware campaigns
Description
Microsoft Exchange Server Remote Code Execution Vulnerability
Key facts
- Published
- 14 Feb 2023
- Last changed
- 19 Aug 2026
- Assigned by
- microsoft
- KEV added
- 13 Apr 2026
- KEV fix due
- 27 Apr 2026
- Used in ransomware
- Yes, according to CISA
- EPSS
- 59.294% likely to be exploited in the next 30 days, higher than 99.134% of CVEs (scores for 15 Nov 2026)
- SSVC (CISA)
- Exploitation: active; Automatable: no; Technical impact: total
Severity scores
Each score is shown as its source gave it. They are not averaged or merged.
- 8.8CVSS 3.1, Highfrom the CNA (microsoft)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
What to do
- Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.CISA KEV required action
Historical context and remediation
This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.
No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.
Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.
Affected products
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Microsoft Exchange Server 2013 Cumulative Update 23 |
|
| Microsoft | Microsoft Exchange Server 2016 Cumulative Update 23 |
|
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 11 |
|
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 12 |
|
Timeline
- 14 Feb 2023 Published
- 13 Apr 2026 CVE-2023-21529 added to CISA KEV
- 13 Apr 2026 Added to the CISA KEV catalogue