CVE-2021-20038
KEVRansomware UseSonicWall SMA 100 Appliances Stack-Based Buffer Overflow Vulnerability
Description
SonicWall SMA 100 devies are vulnerable to an unauthenticated stack-based buffer overflow vulnerability where exploitation can result in code execution.
A Stack-based buffer overflow vulnerability in SMA100 Apache httpd server's mod_cgi module environment variables allows a remote unauthenticated attacker to potentially execute code as a 'nobody' user in the appliance. This vulnerability affected SMA 200, 210, 400, 410 and 500v appliances firmware 10.2.0.8-37sv, 10.2.1.1-19sv, 10.2.1.2-24sv and earlier versions.
CVSS 3.1 vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HPublishedDec 8, 2021
Last modifiedJun 17, 2026
Added to KEVJan 28, 2022
Remediation dueFeb 11, 2022
References
- github.com/jbaines-r7/badbloodExploitThird Party Advisory
- psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0026Vendor Advisory
- rapid7.com/blog/post/2022/01/11/cve-2021-20038-42-sonicwall-sma-100-multiple-vulnerabilities-fixed-2/ExploitThird Party Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20038US Government Resource
0 recent articles mention this CVE
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Risk assessment · Critical
Actively exploited and used by ransomware crews. Patch immediately.
- Exploitation
- Confirmed in the wild (CISA KEV)
- Federal remediation deadline
- Overdue by 1719 days
- Ransomware
- Used in known ransomware campaigns
- CVSS
- 9.8 CRITICAL
- EPSS (30-day exploit probability)
- 99.9% · top 1% of all CVEs
- Weakness
- CWE-121
- Attack vector
- Network, remotely reachable
- Preconditions
- No privileges and no user interaction
Recommended actions
- 1.Apply updates per vendor instructions.
- 2.Treat as emergency change: patch or isolate internet-facing instances first.
- 3.Review exposure: confirm which instances are reachable from the internet and restrict access until patched.
- 4.Hunt for compromise: review logs for the disclosure window, not just from the patch date.
- 5.Verify offline/immutable backups and segment the affected systems. This flaw is used for ransomware initial access.
Assessment is derived automatically from the live signals above; verify against your own asset inventory.