# CVE-2020-5135: SonicWall SonicOS Buffer Overflow

> Remote attackers can cause denial of service or execute arbitrary code on SonicWall firewalls via a buffer overflow in SonicOS.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Yes, since 15 Mar 2022 (CISA KEV), used in ransomware
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Oct 2020
- **Updated:** 21 Oct 2025
- **Also known as:** GHSA-vw5m-894x-7rp4

## What is CVE-2020-5135?

CVE-2020-5135 is a critical memory corruption vulnerability in Sonicwall Sonicos, published on 12 Oct 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-120 (Buffer Copy without Checking Size of Input)

## Which versions are affected by CVE-2020-5135?

It affects 2 products.


Products: Sonicwall Sonicos, Sonicwall Sonicosv.

## How do I fix CVE-2020-5135?

No fix has been published for CVE-2020-5135 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 5 Apr 2022.

## Is CVE-2020-5135 being exploited?

Yes. Attackers have exploited CVE-2020-5135 in the wild since at least 15 Mar 2022, including in ransomware campaigns.

## Other vulnerabilities in Sonicwall Sonicos

- [CVE-2024-40766](https://insights.sbomify.com/CVE-2024-40766/): SonicWall SonicOS Improper Access Control (critical 9.3, exploited in the wild)
- [CVE-2024-53704](https://insights.sbomify.com/CVE-2024-53704/): SonicWall SonicOS SSLVPN Improper Authentication (high 8.2, exploited in the wild)
- [CVE-2025-40600](https://insights.sbomify.com/CVE-2025-40600/): Denial of service in SonicOS (critical 9.8)
- [CVE-2024-22394](https://insights.sbomify.com/CVE-2024-22394/): Auth bypass in SonicOS (critical 9.8)
- [CVE-2022-22274](https://insights.sbomify.com/CVE-2022-22274/): Memory corruption in SonicOS (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-5135 and fix it if it is affected.

What it is: CVE-2020-5135 is a critical memory corruption vulnerability in Sonicwall Sonicos, published on 12 Oct 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2020-5135 in the wild since at least 15 Mar 2022, including in ransomware campaigns.

Affected product: Sonicwall Sonicos. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2020-5135/ (Markdown: https://insights.sbomify.com/CVE-2020-5135/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-5135
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-5135
- OSV: https://osv.dev/vulnerability/CVE-2020-5135

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-5135/
Summaries are generated and may contain mistakes; the official description above is the record.