CVE-2021-20035 — Sma 200 Firmware
MEDIUMCVE-2021-20035 is a medium-severity (CVSS 6.5) OS Command Injection vulnerability in sonicwall sma 200 firmware. It is in CISA's Known Exploited Vulnerabilities catalog (added 2025-04-16) — treat it as actively exploited and patch now. A fix is available — see the affected versions and patch details below.
Improper neutralization of special elements in the SMA100 management interface allows a remote authenticated attacker to inject arbitrary commands as a 'nobody' user which potentially leads to DoS.
Exploitation Status
Actively exploited in the wild
- Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2025-04-16. Federal agencies were required to remediate by 2025-05-07.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2021-20035.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2021-20035 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 395,249 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Description
Improper neutralization of special elements in the SMA100 management interface allows a remote authenticated attacker to inject arbitrary commands as a 'nobody' user which potentially leads to DoS.
Affected Products
sma 200 firmwaresonicwallsma 210 firmwaresonicwallsma 400 firmwaresonicwallsma 410 firmwaresonicwallsma 500vsonicwallDetection & mitigation playbook
Vendor / applianceDetect
Inventory every sonicwall sma 200 firmware deployment and check each version against the affected-products list above.
Fix
Apply the sonicwall sma 200 firmware security patch or hotfix for CVE-2021-20035 on the affected version, following the vendor advisory for your exact build.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.
Frequently Asked Questions
Is CVE-2021-20035 being exploited in your environment?
Detect and block the exploit chain at execution, on systems you cannot patch yet.