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

CVE-2021-20038 is rated critical with a CVSS v3.1 base score of 9.8 and affects SonicWall SMA 100 Appliances, along with 5 other products in NVD’s configuration data. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available. CISA added it to its Known Exploited Vulnerabilities catalog on 2022-01-28, which means exploitation in the wild has been observed.

Vulnerability 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.

Severity breakdown

CVSS v3.1 9.8: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

  • Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
  • Attack complexity: Low. No special conditions; the attack can be repeated reliably.
  • Privileges required: None. No account or prior access is needed.
  • User interaction: None. No action from any user is needed.
  • Scope: Unchanged. Impact stays within the vulnerable component.
  • Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
  • Integrity impact: High. Total loss of integrity; data or system state can be fully modified.
  • Availability impact: High. Total loss of availability; the component can be shut down.

Underlying weakness

CWE-121: Stack-based Buffer Overflow

The product writes past the end of a buffer that was allocated on the stack.

CWE-787: Out-of-bounds Write

The product writes data past the end, or before the beginning, of the intended buffer.

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 410 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 500v Firmware: 10.2.0.8-37sv; 10.2.1.1-19sv; 10.2.1.2-24sv

References