CVE-2021-20027 Memory corruption in SonicOS

What is CVE-2021-20027?

CVE-2021-20027 is a high-severity memory corruption vulnerability in Sonicwall Sonicos, published on 14 Jun 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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.

Weakness: CWE-120

Which versions are affected by CVE-2021-20027?

It affects 1 product.

Products include Sonicwall Sonicos.

How do I fix CVE-2021-20027?

No fix has been published for CVE-2021-20027 yet. Limit exposure of the affected software until one is available.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2021-20027 being exploited?

There is no known exploitation of CVE-2021-20027 in the wild and no public exploit code.

Other vulnerabilities in Sonicwall Sonicos

• CVE-2020-5135 SonicWall SonicOS Buffer Overflow Exploited Critical 9.8
• CVE-2024-40766 SonicWall SonicOS Improper Access Control Exploited Critical 9.3
• CVE-2024-53704 SonicWall SonicOS SSLVPN Improper Authentication Exploited High 8.2
• CVE-2025-40600 Denial of service in SonicOS Critical 9.8
• CVE-2024-22394 Auth bypass in SonicOS Critical 9.8

All Sonicwall Sonicos vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-j2f2-fj3p-8c94.