CVE-2021-20048: SonicWall SonicOS

High severity, CVSS 8.8. EPSS: 1.9% chance of exploitation in the next 30 days.

A Stack-based buffer overflow in the SonicOS SessionID HTTP response header allows a remote authenticated attacker to cause Denial of Service (DoS) and potentially results in code execution in the firewall. This vulnerability affected SonicOS Gen 5, Gen 6 and Gen 7 firmware versions.

Affected products

• SonicWall SonicOS: up to and including 7.0.1-r1456; up to and including 7.0.1-5023-1349; up to and including 7.0.1-5018-r1715; up to and including 6.5.4.8; up to and including 6.5.1.13-1n; up to and including 6.0.5.3-94o; …

Published 2022-01-10. Last modified 2026-06-17.