CVE-2021-20016

CVE-2021-20016 is an unauthenticated SQL injection flaw (CWE-89) in the SonicWall SSL-VPN service on SMA 100 appliances. It is triggered remotely by malicious, unauthenticated requests to the appliance's web interface, allowing SQL injection against the backend database. Successful exploitation gives the attacker credential access — harvesting valid user credentials that can then be used to log into the SSL-VPN and pivot into the victim network. Any organization running an internet-facing SonicWall SSLVPN SMA100 appliance is affected, and CISA notes known ransomware use of this flaw. It was added to the CISA Known Exploited Vulnerabilities catalog on 2021-11-03 and carries a 40% EPSS probability of exploitation within 30 days (99th percentile), so it should be treated as actively exploited even though no public proof-of-concept is known.

What to do: Apply the SonicWall firmware update per vendor instructions, as required by the CISA KEV listing. Because ransomware operators are known to exploit this flaw, review SMA100 authentication and admin logs for unfamiliar logins, rotate exposed credentials, and restrict the appliance to trusted source IPs until it is patched. CVSS has not yet been scored, but the 40% EPSS (99th percentile) and KEV status warrant immediate patching of all internet-exposed units.