CVE-2021-20048 Memory corruption in SonicOS

What is CVE-2021-20048?

CVE-2021-20048 is a high-severity memory corruption vulnerability in Sonicwall Sonicos, published on 7 Jan 2022. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

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.

Weakness: CWE-787, CWE-121

Which versions are affected by CVE-2021-20048?

It affects 1 product.

Products include Sonicwall Sonicos.

How do I fix CVE-2021-20048?

No fix has been published for CVE-2021-20048 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-2021-20048 being exploited?

There is no known exploitation of CVE-2021-20048 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-248v-73qf-wh7x.