# CVE-2026-88771: Citrix NetScaler Improper Input Validation Vulnerability

- Exploited (CISA KEV): yes, added 2026-09-27
- Published: 2026-09-27
- CVSS: 9.5 CRITICAL (v4.0)
- EPSS: 82.2% (100th percentile)
- CWE: CWE-20

Improper input validation vulnerability in Citrix NetScaler ADC and Citrix NetScaler Gateway.

This issue affects ADC: before 14.1-73.37, before 13.1-64.23, before 14.1-73.37 FIPS, and before 13.1.37.279 FIPS and NDcPP; Gateway: before 14.1-73.37 and before 13.1-64.23 leading to an unauthenticated attacker to execute arbitrary commands.

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

| Vendor | Status | First rule | Days after publication |
|---|---|---|---|
| Cloudflare | Blocks by default | 2026-10-01 | 4 |
| AWS | No public claim | — | — |
| Microsoft Azure | No public claim | — | — |
| Google Cloud | No public claim | — | — |
| Fastly | Before feed history | — | — |
| F5 | Rule published | 2026-10-21 | 24 |
| Akamai | No public source | — | — |
| OWASP CRS | No public claim | — | — |

### Cloudflare

- 2026-10-01 · new · rule 6802845374ea41a289fd4f43827ab216 · default Block
  > Citrix Netscaler ADC and Gateway - Improper input validation - CVE:CVE-2026-88771. Previous action: N/A. New action: Block. This is a new detection.
  Source: https://developers.cloudflare.com/changelog/post/2026-10-01-emergency-waf-release/

### F5

- 2026-10-21 · new · rule 200103695
  > Added: signature 200103695 "Citrix Netscaler Remote Code Execution (2)" (Command Execution, risk High), systems: Citrix. References: CVE-2026-88771.
  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-2026-88771 · JSON: https://cve.vigilbase.com/api/v1/cves/CVE-2026-88771