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HighPublic exploit

Authenticated Command Injection in SonicWall SMA100 /cgi-bin/viewcert

IdentifiersCVE-2021-20039CWE-78· Improper Neutralization of Special…

CVE-2021-20039 is an authenticated command injection vulnerability in the SonicWall SMA 100 series management interface, specifically in the '/cgi-bin/viewcert' endpoint when handling POST requests. The issue is caused by improper neutralization of special elements in attacker-controlled input, allowing a remote authenticated attacker to inject arbitrary operating system commands. The vulnerability affects SMA 200, SMA 210, SMA 400, SMA 410, and SMA 500v appliances. The provided content states the flaw allows command execution via the management interface and is associated with post-authentication remote code execution behavior.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows a remote authenticated attacker to execute arbitrary commands on the affected appliance. The supplied content indicates execution may occur as a privileged context sufficient for full device takeover, with reporting describing command injection as root and compromise of the appliance. This can enable complete administrative control, credential access, persistence, further lateral movement through the VPN appliance, and use of the device as a foothold into the victim environment.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, restrict access to the SMA management interface to trusted administrative networks only, minimize the number of accounts with management access, enforce MFA for administrators, rotate credentials, and monitor for signs of compromise. The content also notes broader SonicWall guidance to review PSIRT documentation, use vendor support resources, and, where compromise is suspected, perform firmware upgrades and additional incident-response actions. However, patching is the primary mitigation.

Remediation

Patch, then assume compromise.

Upgrade affected SonicWall SMA 100 series appliances to the latest vendor-provided fixed firmware referenced in SonicWall's PSIRT advisory and available through MySonicWall. The content indicates SonicWall released patches covering CVE-2021-20039 along with related SMA100 vulnerabilities and urged customers to apply them immediately.
PUBLIC EXPLOITS

Exploits

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VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
SonicwallSma 200 Firmwareoperating_system
SonicwallSma 210 Firmwareoperating_system
SonicwallSma 400 Firmwareoperating_system
SonicwallSma 410 Firmwareoperating_system
SonicwallSma 500v Firmwareoperating_system

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What this page doesn’t show

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Exposure mapping

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Threat actor evidence

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Associated malware1

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity

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