# CVE-2025-55315: ASP.NET Security Feature Bypass Vulnerability

- Exploited (CISA KEV): no
- Published: 2025-10-14
- CVSS: 9.9 CRITICAL (v3.1)
- EPSS: 66.5% (99th percentile)
- CWE: CWE-444

Inconsistent interpretation of http requests ('http request/response smuggling') in ASP.NET Core allows an authorized attacker to bypass a security feature over a network.

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

| Vendor | Status | First rule | Days after publication |
|---|---|---|---|
| Cloudflare | No public claim | — | — |
| AWS | No public claim | — | — |
| Microsoft Azure | No public claim | — | — |
| Google Cloud | No public claim | — | — |
| Fastly | Before feed history | — | — |
| F5 | Rule published | 2025-12-03 | 50 |
| Akamai | No public source | — | — |
| OWASP CRS | No public claim | — | — |

### F5

- 2025-12-03 · new · rule 200020232
  > Added: signature 200020232 "ASP.NET Core Request Smuggling" (HTTP Parser Attack, risk High), systems: ASP.NET. References: CVE-2025-55315.
  Source: https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog
- 2025-12-04 · updated · rule 200020232
  > Updated: signature 200020232 "Chunk-Extension Request Smuggling" (HTTP Parser Attack, risk High), systems: ASP.NET. References: CVE-2025-55315, CVE-2025-22871.
  Source: https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog
- 2026-07-07 · updated · rule 200020232
  > Updated: signature 200020232 "Chunk-Extension Request Smuggling" (HTTP Parser Attack, risk High), systems: ASP.NET. References: CVE-2025-55315, CVE-2025-22871.
  Source: https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog
- 2026-09-16 · updated · rule 200020232
  > Updated: signature 200020232 "Chunk-Extension Request Smuggling" (HTTP Parser Attack, risk High), systems: ASP.NET, Other Web Server, Apache Tomcat. References: CVE-2025-55315, CVE-2025-22871, CVE-2026-24880.
  Source: https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog

"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-2025-55315 · JSON: https://cve.vigilbase.com/api/v1/cves/CVE-2025-55315