CVE Intel / CVE-2021-26855
CVE-2021-26855
exchange server · microsoft
⚠
Actively exploited in the wild. Listed in the CISA Known Exploited Vulnerabilities catalogue: exploitation confirmed in the wild. Patch on priority.
What it is
Microsoft Exchange Server Remote Code Execution Vulnerability
Live exploitation on the huntback network (30 days)
34
attempts captured
18
distinct source IPs
2026-09-28
last seen
huntback carries a network signature for this CVE. Exploitation attempts are detected on the decoy fleet in real time.
How huntback helps
Deploy a decoy that emulates exchange server and you will see every attempt at this CVE the moment it lands, with the full payload, the attacker's infrastructure, and any stage-2 loader. Then huntback can scan the attacker back.
CVSSn/a Critical
EPSS1.00 (99% pct)
In CISA KEVyes
Publishedn/a
Network detectableyes, signatured
Public exploitExploitDB, Metasploit