# CVE-2025-52691: SmarterTools SmarterMail Unrestricted Upload of File with Dangerous Type Vulnerability

- Exploited (CISA KEV): yes, added 2026-01-26, known ransomware use
- Published: 2025-12-29
- CVSS: 10 CRITICAL (v3.1)
- EPSS: 85.7% (100th percentile)
- CWE: CWE-434

Successful exploitation of the vulnerability could allow an unauthenticated attacker to upload arbitrary files to any location on the mail server, potentially enabling remote code execution.

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

| Vendor | Status | First rule | Days after publication |
|---|---|---|---|
| Cloudflare | Blocks by default | 2026-03-02 | 63 |
| AWS | No public claim | — | — |
| Microsoft Azure | No public claim | — | — |
| Google Cloud | No public claim | — | — |
| Fastly | Before feed history | — | — |
| F5 | No public claim | — | — |
| Akamai | No public source | — | — |
| OWASP CRS | No public claim | — | — |

### Cloudflare

- 2026-03-02 · new · rule 0f282f3c89614779966faf52966ec6b1 · default Block
  > SmarterMail - Arbitrary File Upload - CVE-2025-52691. Previous action: Log. New action: Block. This is a new detection.
  Source: https://developers.cloudflare.com/changelog/post/2026-03-02-waf-release/

## Our test (measured)

- OWASP Core Rule Set 4.25.0, paranoia level 1, anomaly threshold 5, default CRS settings: blocked (1 of 1 requests blocked), template CVE-2025-52691, 2026-11-02
- OWASP Core Rule Set 4.25.0, paranoia level 2, anomaly threshold 5, default CRS settings: blocked (1 of 1 requests blocked), template CVE-2025-52691, 2026-11-02

"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-2025-52691 · JSON: https://cve.vigilbase.com/api/v1/cves/CVE-2025-52691