CVE-2021-42321CISA KEVEPSS p99.8%

CVE-2021-42321Microsoft Exchange Server Remote Code Execution Vulnerability

Microsoft / Exchange

Description

An authenticated attacker could leverage improper validation in cmdlet arguments within Microsoft Exchange and perform remote code execution.

Scoring

CVSS 8.8 ()
VectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS91.74% probability of exploitation · percentile 99.8% · 2026-09-26T12:00:22Z
Last modified2026-08-19

CISA KEV entry

Added to KEV: 2021-11-17

(incoming)1

TypeTargetConfidenceTier
KEVEntryMicrosoft Exchange Server Remote Code Execution Vulnerabilitykev-cve-2021-423210%live

Related by meaning· 6

Nearest entities by semantic similarity across the cs-graph corpus.

CVE
Microsoft Exchange Server Information Disclosure Vulnerability
CVE
CVE-2026-45583
CVE
Microsoft Exchange Server Deserialization of Untrusted Data Vulnerability
CVE
Microsoft Exchange Server Privilege Escalation Vulnerability
CVE
Microsoft Exchange Server Validation Key Remote Code Execution Vulnerability
CVE
Microsoft Exchange Server Security Feature Bypass Vulnerability
Sourced from NVD + CISA KEV + FIRST.org EPSS. Curated for EU compliance use cases by Adam Lundqvist, Founder at SQUR.