CVE-2021-20035 SonicWall SMA100 Appliances: command or code injection
In plain words: The program treats text it receives as instructions instead of plain data. The attacker can run commands on the machine — often the whole device is taken over.
Confirmed exploited by CISA on · US federal patch deadline May 7, 2025
What to do
- Install SonicWall's security update for SMA100 Appliances. If no update exists, follow the vendor's workaround or stop using the product until one ships.
- Patch edge devices first — attackers often start scanning for them within hours of a fix.
- Never expose the device's admin page to the internet.
- After patching a device that was exposed, follow the vendor's compromise checks, end active sessions and change passwords.
Who is affected
Work IT. Aimed mostly at company systems — you are affected through the companies you use, not your own phone.
What's at risk: They face the internet and guard the whole network, so a flaw here can hand attackers a way in — and these devices usually run no antivirus, so break-ins go unnoticed.
The details
- Official name
- SonicWall SMA100 Appliances OS Command Injection Vulnerability
- Product
- SonicWall SMA100 Appliances
- CISA description
- SonicWall SMA100 appliances contain an OS command injection vulnerability in the management interface that allows a remote authenticated attacker to inject arbitrary commands as a 'nobody' user, which could potentially lead to code execution.
- Type of flaw
- Command or code injection (CWE-78)
- Confirmed exploited
- Apr 16, 2025
- US federal patch deadline
- May 7, 2025
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Answering about CVE-2021-20035 ·
Questions about CVE-2021-20035
Is CVE-2021-20035 being exploited?
Yes. CISA added CVE-2021-20035 to its Known Exploited Vulnerabilities catalog on Apr 16, 2025, which means there is reliable evidence of real-world attacks.
How do I fix CVE-2021-20035?
Install SonicWall's security update for SMA100 Appliances. If no update exists, follow the vendor's workaround or stop using the product until one ships. Patch edge devices first — attackers often start scanning for them within hours of a fix.
Am I affected by CVE-2021-20035?
Only if you use SonicWall SMA100 Appliances. Aimed mostly at company systems — you are affected through the companies you use, not your own phone.