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CVE-2020-5135

9.8, critical Known exploited Used in ransomware

SonicWall SonicOS Buffer Overflow Vulnerability

NVD (opens in a new tab) CVE.org (opens in a new tab) CISA KEV catalogue (opens in a new tab)
CVSS
9.8, critical critical CVSS v3.1
EPSS, next 30 days
27% higher than 98% of scored CVEs
Exploitation
Confirmed in the wild
Published
12 Oct 20206 years ago

Known exploited

CISA added this to the Known Exploited Vulnerabilities Catalog on 15 Mar 2022 and links it to ransomware activity. US federal agencies had to remediate by 5 Apr 2022, a deadline that has passed.

Required action. Apply updates per vendor instructions.

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.

Details

Vendor
SonicWall
Product
SonicOS
Weakness
CWE-120 (opens in a new tab)
Status
Analyzed
Updated
17 Jun 2026
Assigner
PSIRT@sonicwall.com

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

References 2

Advisories 1

Other references 1

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Other SonicWall CVEs

Every SonicWall CVE we hold

Same vendor in what we hold, not a known link between the flaws.

  • CVE-2026-83548 SonicWall SMA1000 Appliances Server-Side Request Forgery Vulnerability KEV EPSS 8% 10, critical
  • CVE-2026-83549 SonicWall SMA1000 Appliances OS Command Injection Vulnerability KEV EPSS 10% 7.8, high
  • CVE-2026-15409 SonicWall SMA1000 Appliances Server-Side Request Forgery Vulnerability KEV EPSS 7% 10, critical
  • CVE-2026-15410 SonicWall SMA1000 Appliances Code Injection Vulnerability KEV EPSS 12% 7.2, high
  • CVE-2025-40602 SonicWall SMA1000 Missing Authorization Vulnerability KEV EPSS 3% 6.6, medium
  • CVE-2025-23006 SonicWall SMA1000 Appliances Deserialization Vulnerability KEV EPSS 23% 9.8, critical
  • CVE-2024-53704 SonicWall SonicOS SSLVPN Improper Authentication Vulnerability KEV EPSS 95% 9.8, critical
  • CVE-2024-40766 SonicWall SonicOS Improper Access Control Vulnerability KEV EPSS 18% 9.8, critical

Beyond this page

Is CVE-2020-5135 in your network?

This page tells you how dangerous CVE-2020-5135 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

CVE-2020-5135 is in the CISA catalogue of exploited vulnerabilities: attackers are already exploiting it.

  • EXYS7600 OCELOT

    Find it before attackers do

    Ocelot scans your network on a schedule and reports every vulnerability it finds by its CVE identifier, with its CVSS score and how many of your hosts are affected. A finding like CVE-2020-5135 comes with the devices to patch.

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  • EXYS7950 KONDRA

    Detect it if it's exploited

    Until the patch is applied, Kondra monitors your network, events and endpoints in real time. It keeps an inventory of the software installed on every endpoint, and its anomaly detection rules flag what an attacker does once inside.

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Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 18 Oct 2026, not the live upstream state.