# CVE-2025-53770: Microsoft SharePoint Deserialization of Untrusted Data Vulnerability

- Exploited (CISA KEV): yes, added 2025-07-20, known ransomware use
- Published: 2025-07-20
- CVSS: 9.8 CRITICAL (v3.1)
- EPSS: 100.0% (100th percentile)
- CWE: CWE-502

Deserialization of untrusted data in on-premises Microsoft SharePoint Server allows an unauthorized attacker to execute code over a network.
Microsoft is aware that an exploit for CVE-2025-53770 exists in the wild.
Microsoft is preparing and fully testing a comprehensive update to address this vulnerability.  In the meantime, please make sure that the mitigation provided in this CVE documentation is in place so that you are protected from exploitation.

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

| Vendor | Status | First rule | Days after publication |
|---|---|---|---|
| Cloudflare | Blocks by default | 2025-07-21 | 1 |
| AWS | No public claim | — | — |
| Microsoft Azure | No public claim | — | — |
| Google Cloud | No public claim | — | — |
| Fastly | Before feed history | — | — |
| F5 | Rule published | 2025-08-15 | 26 |
| Akamai | No public source | — | — |
| OWASP CRS | No public claim | — | — |

### Cloudflare

- 2025-07-21 · new · rule 34dac2b38b904163bc587cc32168f6f0 · default Block
  > Microsoft SharePoint - Deserialization - CVE:CVE-2025-53770. Previous action: N/A. New action: Block. This is a New Detection
  Source: https://developers.cloudflare.com/changelog/post/2025-07-21-emergency/

### F5

- 2025-08-15 · new · rule 200204026
  > Added: signature 200204026 "Microsoft SharePoint ToolPane Remote Code Execution" (Server Side Code Injection, risk High), systems: SharePoint. References: CVE-2025-49704, CVE-2025-49706, CVE-2025-53770, CVE-2025-53771.
  Source: https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog

## Our test (measured)

- OWASP Core Rule Set 4.25.0, paranoia level 1, anomaly threshold 5, default CRS settings: blocked (2 of 2 requests blocked), template CVE-2025-53770, 2026-11-02
- OWASP Core Rule Set 4.25.0, paranoia level 2, anomaly threshold 5, default CRS settings: blocked (2 of 2 requests blocked), template CVE-2025-53770, 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-2025-53770 · JSON: https://cve.vigilbase.com/api/v1/cves/CVE-2025-53770