CVE-2021-20038
SonicWall SMA 100 Appliances Stack-Based Buffer Overflow Vulnerability
- Critical 9.8
- Exploited: added to CISA KEV 28 Jan 2022
- Used in ransomware campaigns
Description
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.
Key facts
- Published
- 8 Dec 2021
- Last changed
- 21 Oct 2025
- Assigned by
- sonicwall
- KEV added
- 28 Jan 2022
- KEV fix due
- 11 Feb 2022
- Used in ransomware
- Yes, according to CISA
- EPSS
- 99.912% likely to be exploited in the next 30 days, higher than 99.968% of CVEs (scores for 15 Nov 2026)
- SSVC (CISA)
- Exploitation: active; Automatable: yes; Technical impact: total
Severity scores
Each score is shown as its source gave it. They are not averaged or merged.
- 9.8CVSS 3.1, Criticalfrom CISA (ADP container)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
What to do
- Apply updates per vendor instructions.CISA KEV required action
Historical context and remediation
This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.
No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.
Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.
Affected products
| Vendor | Product | Versions |
|---|---|---|
| SonicWall | SonicWall SMA100 |
|
Timeline
- 8 Dec 2021 Published
- 28 Jan 2022 CVE-2021-20038 added to CISA KEV
- 28 Jan 2022 Added to the CISA KEV catalogue