SonicWall SMA 100: CVE-2021-20038: Unauthenticated Stack-based Buffer Overflow

A critical vulnerability (CVSS 9.8) in SMA 100 appliances, which includes SMA 200, 210, 400, 410 and 500v could allow a remote unauthenticated attacker the ability to cause Stack based Buffer Overflow which can potentially lead to malicious code execution in the device. It was also noticed that SMA 100 users with WAF enabled/licensed are also impacted by this vulnerability. The vulnerability is due to `cgi_build_command` method that appends all the environment variables onto a single stack. This method is vulnerable to Stack-Based Buffer Overflow. There is no evidence that this vulnerability is being exploited in the wild. SonicWall strongly urges that organizations follow the guidance below to patch SMA 100 series products, which include SMA 200, 210, 400, 410 and 500v.