How severe is CVE-2021-20016?

CVE-2021-20016 has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

Which products are affected by CVE-2021-20016?

Affected package information for CVE-2021-20016 is not yet fully mapped. Check the official advisory links for details.

How do I patch CVE-2021-20016?

Apply the sonicwall sma 100 firmware security patch or hotfix for CVE-2021-20016 on the affected version, following the vendor advisory for your exact build.

How do I detect CVE-2021-20016 across my infrastructure?

Inventory every sonicwall sma 100 firmware deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for exploitation at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.

How do I mitigate CVE-2021-20016 if there is no patch (or I can't update yet)?

Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.

How does O3 Security protect against CVE-2021-20016?

O3 detects and blocks CVE-2021-20016 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.

Is CVE-2021-20016 actively exploited in the wild?

Yes. There are 2 known exploit references for CVE-2021-20016, including 2 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-20016?

CVE-2021-20016 has an EPSS (Exploit Prediction Scoring System) score of 37.0%, placing it in the 98th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score warrants monitoring and prompt remediation.

Is CVE-2021-20016 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2021-20016 (SonicWall SSLVPN SMA100 SQL Injection Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2021-11-03. CISA required all US federal civilian agencies to remediate this vulnerability by 2021-11-17. The required action was: Apply updates per vendor instructions. This CVE has been used in known ransomware campaigns. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2021-20016?

CVE-2021-20016 is classified as SQL Injection (CWE-89). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

Which products and versions are affected by CVE-2021-20016?

CVE-2021-20016 affects sonicwall sma 100 firmware; sonicwall sma 200 firmware; sonicwall sma 210 firmware; sonicwall sma 400 firmware, and 2 more product(s). Check the affected-products list on this page against your deployed version to confirm exposure.

When was CVE-2021-20016 published, and has it been updated?

CVE-2021-20016 was published on February 4, 2021 and was last updated on June 17, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CISA KEV·Added 2021-11-03 — agencies required to remediate by 2021-11-17 · Ransomware

CVE-2021-20016

CRITICAL

A SQL-Injection vulnerability in the SonicWall SSLVPN SMA100 product allows a remote unauthenticated attacker to perform SQL query to access username password and other session related…

Published

Feb 4, 2021

Updated

Jun 17, 2026

Affected

0 pkgs

Patched

None yet

Exploits

2 known

EPSS Exploitation Probability

via FIRST.org ↗

37.0%probability of exploitation in next 30 days

Moderate Risk98th percentile-3.09%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Description

A SQL-Injection vulnerability in the SonicWall SSLVPN SMA100 product allows a remote unauthenticated attacker to perform SQL query to access username password and other session related information. This vulnerability impacts SMA100 build version 10.x.

Affected Products

6 products · 6 configurations

sma 100 firmwaresonicwall

≥ 10.0.0.0 && < 10.2.0.5-d-29sv

range

sma 200 firmwaresonicwall

all

sma 210 firmwaresonicwall

all

sma 400 firmwaresonicwall

all

sma 410 firmwaresonicwall

all

Application

sma 500vsonicwall

all

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

A SQL-Injection vulnerability in the SonicWall SSLVPN SMA100 product all…

cisa.govCISANov 2021

A SQL-Injection vulnerability in the SonicWall SSLVPN SMA100 product all…

twitter.comAPIJan 2021

Detection & mitigation playbook

Vendor / appliance

Detect
Inventory every sonicwall sma 100 firmware deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for exploitation at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.
Fix
Apply the sonicwall sma 100 firmware security patch or hotfix for CVE-2021-20016 on the affected version, following the vendor advisory for your exact build.
Workarounds
Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.
How O3 protects you
O3 detects and blocks CVE-2021-20016 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.

Tailored to CVE-2021-20016. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

O3 Security · Runtime Protection

Is CVE-2021-20016 being exploited in your environment?

O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2021-20016 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.

Protect my workloads How runtime protection works