CVE-2020-5135VulnerabilityPublished 03/15/2022Updated 10/24/2026

CVE-2020-5135: SonicWall SonicOS Buffer Overflow Vulnerability

Affects SonicWall SonicOSSource CISA KEV

Severity

High

No CVSS score published yet

Exploitation: Actively exploited – in CISA KEV since 03/15/2022
KEV deadline: 04/05/2022
Ransomware: Used in ransomware campaigns
EPSS: 26.9% chance of exploitation in 30 days – higher than 98% of CVEs

What to do

CISA required action

Apply updates per vendor instructions.

nvd.nist.gov/vuln/detail/CVE-2020-5135 (opens in a new tab)

Description

CVE-2020-5135 is a buffer overflow vulnerability in SonicWall SonicOS that allows remote attackers to cause Denial of Service (DoS) and potentially execute arbitrary code by sending malicious requests to the firewall. This vulnerability has been exploited in the wild and is known to have been used in ransomware campaigns. No specific affected versions or patch information is provided in the available data.

Summary

This vulnerability involves a buffer overflow in SonicWall SonicOS, which can be triggered remotely by sending crafted requests to the firewall. Successful exploitation can lead to DoS conditions or arbitrary code execution, posing significant risk to affected systems. The vulnerability is tracked as CVE-2020-5135 and is associated with CWE-120 (Classic Buffer Overflow). It has been observed in active exploitation scenarios, including ransomware campaigns.

Impact

Exploitation can cause denial of service on SonicWall SonicOS devices and may allow attackers to execute arbitrary code remotely. This can lead to compromised firewall integrity, potential network breaches, and facilitation of ransomware attacks.

Mitigation

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is confirmed, monitor vendor communications closely and apply any recommended temporary mitigations. Given the known exploitation in the wild, prioritize investigation and containment measures for affected SonicWall SonicOS devices.

Weaknesses

CWE-120Buffer Copy without Size Check (opens in a new tab)

What to do

Description

AnalysisAI-generated, updated 10/24/2026, 10:55:34 UTC

Weaknesses

References

Related threats