CVE-2023-21529

CISA KEV RANSOMWARE

ACT NOW Priority: 0.00 BB Relevance: 10/100

Published: N/A Modified: N/A First seen: 2026-10-29 Status: pending_score

Microsoft Exchange Server contains a deserialization of untrusted data that allows an authenticated attacker to achieve remote code execution.

Vendor / Product Microsoft — Exchange Server

Date Added 2026-04-13

Remediation Due 2026-04-27

Ransomware Use CONFIRMED

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21529 ; https://nvd.nist.gov/vuln/detail/CVE-2023-21529

CWE-502

US Government Resource

Technical Description

Patch Vendor Advisory

10 / 100

✓ Known exploited (KEV)
✓ High exploitation probability

Unscored

59.29%

Raw Score 0.592940

Percentile 99.1%

Date 2026-10-28

kev ref →