AUGUST 5, 2026
Live Feed
Back to database
Case File

CVE-2021-42321

HIGH · CVSS 8.8 EPSS 90.39% CISA KEV · Actively Exploited Public Exploit

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2021-11-10 · Last synced 2026-08-04

CyberRota Analysis

This is a high severity vulnerability with a CVSS score of 8.8. It affects Microsoft, Exchange. It is listed in CISA's Known Exploited Vulnerabilities catalog, indicating confirmed active exploitation in the wild. Public exploit code or proof-of-concept references have been detected in its references. Its EPSS score suggests a 90.4% probability of exploitation in the next 30 days. It may be remotely exploitable.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

Detected Signals
remote code execution code execution

Note: these links are listed for security research and verification purposes only.

CISA KEV Details

Status: This CVE is listed in CISA's Known Exploited Vulnerabilities catalog.

Ransomware use: Known

Added to KEV: 2021-11-17

Required action: Apply updates per vendor instructions.

CVE
CVE-2021-42321
Severity
HIGH
CVSS
8.8
EPSS
90.39%
Microsoft Exchange

Original NVD Description

Microsoft Exchange Server Remote Code Execution Vulnerability

Related CVEs

Other vulnerabilities affecting the same vendor(s)