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CVE-2026-88771

Citrix NetScaler•CRITICAL · CVSS 9.8• In the wild In CISA KEV

What is CVE-2026-88771?

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.

CVSS9.8 NVD 3.1

SeverityCRITICAL

Exploitation In the wild In CISA KEV

EPSS82% · P100

Triage statusActive Exploit

ActionPatch immediately

CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CWECWE-20

NVD published2026-09-27

NVD last modified2026-09-29

Timeline

2026-09-27Published to the U.S. National Vulnerability Database (NVD)
2026-09-27Added to the CISA Known Exploited Vulnerabilities (KEV) catalog
2026-09-28First covered in a defend.network daily briefing
2026-09-29NVD record last updated
2026-09-30CISA federal remediation deadline (BOD 26-04)

CISA Known Exploited Vulnerability

Citrix NetScaler Improper Input Validation Vulnerability

Added to KEV2026-09-27

Federal patch deadline2026-09-30

Known ransomware useUnknown

Affected product

Citrix NetScaler

NVD also lists CPE entries for: Citrix Netscaler Application Delivery Controller, Citrix Netscaler Gateway

Remediation Steps

Apply the vendor security update for Citrix Netscaler Application Delivery Controller as a priority.
Restrict network exposure of the affected service to trusted sources until patched.
Review logs and detections for indicators of exploitation.
Confirm fixed versions against the official vendor advisory before deploying.

References

Referenced in our briefings & reports

Vulnerability Priority Report – Week 4 of October 2026 (October 26 – November 1)
Vulnerability Priority Report – Week 3 of October 2026 (October 19 – 25)
Vulnerability Priority Report – Week 2 of October 2026 (October 12 – 18)
Vulnerability Priority Report – Week 1 of October 2026 (October 5 – 11)
Vulnerability Priority Report – Week 4 of September 2026 (September 28 – October 4)
Apple zero-day, Microsoft mega-patch (974 CVEs), ShinyHunters Oracle escalation (2026-09-29)
Citrix NetScaler, Oracle, Cloudflare RCEs under active exploitation; WAF bypasses escalate risks (2026-09-28)

Related vulnerabilities

CVE-2026-88779 – Citrix NetScaler (same product)
CVE-2026-88772 – Citrix NetScaler (same product)
CVE-2026-19490 – Citrix NetScaler (same product)
CVE-2026-3055 – Citrix NetScaler (same product)
CVE-2026-8451 – Citrix Netscaler (same product)
CVE-2026-8452 – Citrix NetScaler ADC And NetScaler Gateway (same product)

Citrix: 27 known exploited vulnerabilities (CISA KEV) →

Browse all tracked CVEs in the defend.network CVE database →

🤖 This CVE page is generated by defend.network from NVD, CISA KEV, EPSS, and our verified daily briefings. Severity and exploitation data come from official sources; always verify remediation steps against the official vendor advisory before acting in production.