CVE-2026-88771: Citrix NetScaler (Critical, CVSS 9.5)
- CVSS
- 9.5 Critical (v4.0)
- EPSS
- 1.1% chance of exploitation in the next 30 days (higher than 64.9% of CVEs)
- Exploited in the wild
- Yes, on CISA’s KEV list since Sep 27, 2026
- Public exploit
- Yes, reported in a Metasploit module and 10 GitHub repositories
- Weakness
- CWE-20
- Vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H- Published
- Sep 27, 2026
- CISA fix-by date
- Sep 30, 2026 (for US federal agencies)
What it is
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.
Description from the National Vulnerability Database.
What to do
CISA: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating
Check whether you run Citrix NetScaler, then apply the vendor’s fix or mitigation from the advisories below. Because this flaw is exploited or has public exploit code, treat it as urgent and check for signs of compromise, not just the patch level.
Advisories and fixes
ThreatRoundup coverage
NetScaler Crash Handler Turned Into a Root Shell, Rapid7 Finds
Sources: NVD, FIRST EPSS, CISA KEV, and public exploit databases (availability only). ThreatRoundup reports whether public exploit code exists but never links to it: fake proof-of-concepts that infect security researchers are common. This page updates automatically.