CVE-2023-21529
Microsoft Exchange Server Deserialization of Untrusted Data Vulnerability
IN CISA KEV
Microsoft Exchange Server contains a deserialization of untrusted data that allows an authenticated attacker to achieve remote code execution.
- Vendor
- Microsoft
- Product
- Exchange Server
- CVSS
- No score recorded (no NVD record loaded for this entry)
- CWE
- CWE-502
- Published
- Not recorded
- NVD modified
- Not recorded
CISA KEV
- Date added
- 2026-04-13
- Due date
- 2026-04-27
- Ransomware use
- Known
- 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.
EPSS
59.3% chance of exploitation in the next 30 days (percentile 99th)
FIRST EPSS, updated 17 Oct 2026. About EPSS
CVSS is severity, EPSS is likelihood, KEV means already exploited. EPSS is a statistical probability, not a certainty: a low score does not make a bug safe, and a high one does not prove it is being exploited.
Data last updated 18 Oct 2026. Sources: NVD API 2.0, CISA KEV catalog, FIRST EPSS. Links: NVD, CISA KEV. Metadata only. ThreatWire does not host exploit code.