CVE-2020-5135: SonicWall SonicOS Buffer Overflow Vulnerability

Vulnerability summary

CVE-2020-5135 is a critical (CVSS 9.8) Classic Buffer Overflow vulnerability in SonicWall SonicOS. It is known to be exploited: CISA lists it, first on 15-03-2022. It has been used in ransomware campaigns. EPSS estimates a 26.87% chance of exploitation in the next 30 days, higher than 98% of scored vulnerabilities.

Timeline

1. 12-10-2020
   PublishedVulnerability first disclosed.
2. 15-03-2022
   Added to CISA KEVSonicWall SonicOS Buffer Overflow Vulnerability
3. 05-04-2022
   CISA remediation dueApply updates per vendor instructions.
4. 21-10-2025
   Last modifiedVulnerability information updated.

Description

A buffer overflow vulnerability in SonicOS allows a remote attacker to cause Denial of Service (DoS) and potentially execute arbitrary code by sending a malicious request to the firewall. This vulnerability affected SonicOS Gen 6 version 6.5.4.7, 6.5.1.12, 6.0.5.3, SonicOSv 6.5.4.v and Gen 7 version 7.0.0.0.

• CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.