CVE-2021-20027: SonicWall SonicOS

High severity, CVSS 7.5. EPSS: 1.3% chance of exploitation in the next 30 days.

A buffer overflow vulnerability in SonicOS allows a remote attacker to cause a Denial of Service (DoS) by sending a specially crafted request. This vulnerability affects SonicOS Gen5, Gen6, Gen7 platforms, and SonicOSv virtual firewalls.

Affected products

• SonicWall SonicOS: up to and including 7.0.1-r1262; up to and including 7.0.1-r.1219; up to and including 7.0.1-r514; up to and including 5.9.1.13; up to and including 6.5.1.12; up to and including 6.5.4.7; …

Published 2021-06-14. Last modified 2026-06-17.