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CVE-2021-20038: SonicWall SMA 100 Appliances Stack-Based Buffer Overflow Vulnerability

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: yes — in CISA KEV since 2022-01-28
• EPSS: 99.9% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-12-08 · updated 2026-06-17
• Weakness: CWE-121

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.

Affected products

• SonicWall Sma 200 Firmware: 10.2.0.8-37sv, 10.2.1.1-19sv, 10.2.1.2-24sv
• SonicWall Sma 210 Firmware: 10.2.0.8-37sv, 10.2.1.1-19sv, 10.2.1.2-24sv
• SonicWall Sma 400 Firmware: 10.2.0.8-37sv, 10.2.1.1-19sv, 10.2.1.2-24sv
• SonicWall Sma 410 Firmware: 10.2.0.8-37sv, 10.2.1.1-19sv, 10.2.1.2-24sv
• SonicWall Sma 500V Firmware: 10.2.0.8-37sv, 10.2.1.1-19sv, 10.2.1.2-24sv

References

• https://github.com/jbaines-r7/badblood
• https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0026
• https://www.rapid7.com/blog/post/2022/01/11/cve-2021-20038-42-sonicwall-sma-100-multiple-vulnerabilities-fixed-2/
• https://github.com/jbaines-r7/badblood
• https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0026
• https://www.rapid7.com/blog/post/2022/01/11/cve-2021-20038-42-sonicwall-sma-100-multiple-vulnerabilities-fixed-2/
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20038

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