CVE-2023-21529 KEV
8.8
HIGH · CVSS 3.1 · EPSS 59.3% (pctl 99)
Patch first
On CISA KEV — known exploited in the wild, due 2026-04-27.
Description
Microsoft Exchange Server Remote Code Execution Vulnerability
Scoring
| CVSS | 8.8 (HIGH, v3.1) |
|---|---|
| Vector | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| EPSS | 59.29% — more likely to be exploited than 99% of all CVEs |
| Weakness | CWE-502 |
| On CISA KEV | yes — remediate by 2026-04-27 |
| Public exploit | none known |
| Published | 2023-02-14 |
| Last modified | 2026-08-19 |
CISA KEV
| Name | Microsoft Exchange Server Deserialization of Untrusted Data Vulnerability |
|---|---|
| Added | 2026-04-13 |
| Due | 2026-04-27 |
| Vendor / product | Microsoft / Exchange Server |
| Ransomware use | known |
Affected (1)
| Vendor | Product |
|---|---|
| microsoft | exchange server |
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21529
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21529
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-21529
- https://www.microsoft.com/en-us/security/blog/2026/04/06/storm-1175-focuses-gaze-on-vulnerable-web-facing-assets-in-high-tempo-medusa-ransomware-operations/
→ the Explorer · watch your stack · NVD