Microsoft SMBv1 Server Remote Code Execution Vulnerability
What it is
The SMBv1 server in Microsoft allows remote attackers to execute arbitrary code via crafted packets.
Known to be used in ransomware campaigns.Active threat actors have chained this vulnerability into ransomware operations — treat patching as a same-week priority, not a "next maintenance window" task. The coping action is the same one below; the urgency is higher.
Who's affected
Affects anyone running Microsoft SMBv1 server. Microsoft products in a small practice typically sit close to credentials, email, or document workflows — treat the patch as in-scope.
What to do
Apply updates per vendor instructions.
CISA action deadline: April 27, 2022. Federal agencies must complete the required action by this date. For private SMBs the deadline is advisory — but treat it as a strong recommendation, especially if you handle regulated data (HIPAA, GLBA, ABA model rules).
If you don't have someone in-house to verify the patch deployed across every endpoint — or you're not sure whether you're affected — that's exactly the kind of triage we do. Book a free 20-minute triage call.
Severity
CVSS base score: 8.1 — HIGH
Weakness classification: CWE-20
Source
Pulled daily from the public cisagov/kev-data mirror (CC0). View the original entry on cisa.gov. CISA KEV is US-Government public-domain data; we add the SMB-vertical framing and the coping action above.