# CVE-2021-20042: SonicWall SonicWall SMA100

- Exploited (CISA KEV): no
- Published: 2021-12-08
- CVSS: not scored
- EPSS: 3.7% (90th percentile)
- CWE: CWE-441

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.

## Edge WAF coverage (claimed by vendors, not measured)

| Vendor | Status | First rule | Days after publication |
|---|---|---|---|
| Cloudflare | Blocks by default | 2025-05-05 | 1244 |
| AWS | No public claim | — | — |
| Microsoft Azure | No public claim | — | — |
| Google Cloud | Before feed history | — | — |
| Fastly | Before feed history | — | — |
| F5 | Before feed history | — | — |
| Akamai | No public source | — | — |
| OWASP CRS | Before feed history | — | — |

### Cloudflare

- 2025-05-05 · new · rule 616ad0e03892473191ca1df4e9cf745d · default Block
  > SonicWall SMA - Dangerous File Upload - CVE:CVE-2021-20040, CVE:CVE-2021-20041, CVE:CVE-2021-20042. Previous action: Log. New action: Block. This is a New Detection
  Source: https://developers.cloudflare.com/changelog/post/2025-05-05-waf-release/

"No public claim" means no vendor statement names this CVE; "Before feed history" means the CVE is older than the vendor feed. In both cases generic rules may still block it.

HTML: https://cve.vigilbase.com/cve/CVE-2021-20042 · JSON: https://cve.vigilbase.com/api/v1/cves/CVE-2021-20042