# CVE-2021-20041: SonicWall SonicWall SMA100

- Exploited (CISA KEV): no
- Published: 2021-12-08
- CVSS: not scored
- EPSS: 21.2% (98th percentile)
- CWE: CWE-835

An unauthenticated and remote adversary can consume all of the device's CPU due to crafted HTTP requests sent to SMA100 /fileshare/sonicfiles/sonicfiles resulting in a loop with unreachable exit condition. 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-2021-20041 · JSON: https://cve.vigilbase.com/api/v1/cves/CVE-2021-20041