# CVE-2025-5777: Citrix NetScaler ADC and Gateway Out-of-Bounds Read Vulnerability

- Exploited (CISA KEV): yes, added 2025-07-10, known ransomware use
- Published: 2025-06-17
- CVSS: 9.3 CRITICAL (v4.0)
- EPSS: 100.0% (100th percentile)
- CWE: CWE-125

Insufficient input validation leading to memory overread when the NetScaler is configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server

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

| Vendor | Status | First rule | Days after publication |
|---|---|---|---|
| Cloudflare | Rule off by default | 2025-07-21 | 34 |
| AWS | No public claim | — | — |
| Microsoft Azure | No public claim | — | — |
| Google Cloud | No public claim | — | — |
| Fastly | Before feed history | — | — |
| F5 | Rule published | 2025-08-15 | 59 |
| Akamai | No public source | — | — |
| OWASP CRS | No public claim | — | — |

### Cloudflare

- 2025-07-21 · new · rule cd8fa74e8f6f476c9380ae217899130f · default Disabled
  > Citrix Netscaler ADC - Buffer Error - CVE:CVE-2025-5777. Previous action: Log. New action: Disabled. This is a New Detection
  Source: https://developers.cloudflare.com/changelog/post/2025-07-21-waf-release/

### F5

- 2025-08-15 · new · rule 200009336
  > Added: signature 200009336 "Citrix NetScaler Information Disclosure" (Information Leakage, risk High), systems: Citrix. References: CVE-2025-5777.
  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: passed (0 of 1 requests blocked), template CVE-2025-5777, 2026-11-02
- OWASP Core Rule Set 4.25.0, paranoia level 2, anomaly threshold 5, default CRS settings: passed (0 of 1 requests blocked), template CVE-2025-5777, 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-2025-5777 · JSON: https://cve.vigilbase.com/api/v1/cves/CVE-2025-5777