CVE-2021-20038
SonicWall SMA 100 Appliances Stack-Based Buffer Overflow Vulnerability
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 11 February 2022). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
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.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 99.91% probability · 100th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Listed 28 January 2022 · due 11 February 2022 · used in ransomware campaigns
- Weakness
- CWE-121, CWE-787
- Affected
- sonicwall/sma 200 firmware · sonicwall/sma 210 firmware · sonicwall/sma 410 firmware · sonicwall/sma 400 firmware · sonicwall/sma 500v firmware
- Source
- PSIRT@sonicwall.com
EPSS 99.9% since 30 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
CISA notes
Apply updates per vendor instructions. https://nvd.nist.gov/vuln/detail/CVE-2021-20038
References
- https://github.com/jbaines-r7/badbloodExploit, Third Party Advisory
- https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0026Vendor Advisory
- https://www.rapid7.com/blog/post/2022/01/11/cve-2021-20038-42-sonicwall-sma-100-multiple-vulnerabilities-fixed-2/Exploit, Third Party Advisory
- https://github.com/jbaines-r7/badbloodExploit, Third Party Advisory
- https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0026Vendor Advisory
- https://www.rapid7.com/blog/post/2022/01/11/cve-2021-20038-42-sonicwall-sma-100-multiple-vulnerabilities-fixed-2/Exploit, Third Party Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20038US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.