# CVE-2021-20042: Server-side request forgery in SonicWall SMA100

> Unauthenticated attackers can use SonicWall SMA100 appliances as an unintended proxy to bypass firewall rules and access internal resources.

- **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:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 8 Dec 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-7jhp-ff4f-8fx7

## What is CVE-2021-20042?

CVE-2021-20042 is a critical server-side request forgery vulnerability in SonicWall SMA100, published on 8 Dec 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An unauthenticated remote attacker can use SMA 100 as an unintended proxy or intermediary undetectable proxy to bypass firewall rules. This vulnerability affected SMA 200, 210, 400, 410 and 500v appliances.

Weakness: CWE-441 (Unintended Proxy or Intermediary)

## Which versions are affected by CVE-2021-20042?

It affects 5 products.


Products: Sonicwall Sma 200 Firmware, Sonicwall Sma 210 Firmware, Sonicwall Sma 400 Firmware, Sonicwall Sma 410 Firmware, Sonicwall Sma 500v Firmware.

## How do I fix CVE-2021-20042?

No fix has been published for CVE-2021-20042 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-20042 being exploited?

There is no known exploitation of CVE-2021-20042 in the wild and no public exploit code.

## Other vulnerabilities in SonicWall SMA100

- [CVE-2021-20038](https://insights.sbomify.com/CVE-2021-20038/): SonicWall SMA 100 Appliances Stack-Based Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2023-44221](https://insights.sbomify.com/CVE-2023-44221/): SonicWall SMA100 Appliances OS Command Injection (high 7.2, exploited in the wild)
- [CVE-2021-20035](https://insights.sbomify.com/CVE-2021-20035/): SonicWall SMA100 Appliances OS Command Injection (medium 6.5, exploited in the wild)
- [CVE-2022-22273](https://insights.sbomify.com/CVE-2022-22273/): Command injection in SonicWall SRA/SMA100 (critical 9.8)
- [CVE-2021-20045](https://insights.sbomify.com/CVE-2021-20045/): Memory corruption in SonicWall SMA100 (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-20042 and fix it if it is affected.

What it is: CVE-2021-20042 is a critical server-side request forgery vulnerability in SonicWall SMA100, published on 8 Dec 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-20042 in the wild and no public exploit code.

Affected product: SonicWall SMA100. 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-2021-20042/ (Markdown: https://insights.sbomify.com/CVE-2021-20042/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-20042
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-20042
- OSV: https://osv.dev/vulnerability/CVE-2021-20042

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-20042/
Summaries are generated and may contain mistakes; the official description above is the record.