How to fix CVE-2026-88773: citrix netscaler application delivery controller (Metasploit module public)

Inconsistent interpretation of HTTP requests ('HTTP Request/Response smuggling') 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 and NDcPP; Gateway: before 14.1-73.37 FIPS and before 13.1-64.23.

• Severity: CRITICAL (CVSS 4.0 9.3, vector CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:H/SI:H/SA:N).
• Weakness: CWE-444.
• NVD published 2026-09-27, status Analyzed.

Anyone running citrix netscaler application delivery controller in the version ranges below.

• citrix netscaler application delivery controller: from 13.1 up to (not including) 13.1-64.23.
• citrix netscaler application delivery controller: from 13.1 up to (not including) 13.1.37.279.
• citrix netscaler application delivery controller: from 14.1 up to (not including) 14.1-73.37.
• citrix netscaler gateway: from 13.1 up to (not including) 13.1-64.23.
• citrix netscaler gateway: from 14.1 up to (not including) 14.1-73.37.
• citrix netscaler application delivery controller: from 14.1-66.68 up to and including 14.1-73.37.

Version ranges come from the NVD CPE configuration. Confirm against the vendor advisory before you rely on them.

• Metasploit module: exploit/freebsd/http/citrix_netscaler_cve_2026_88771 (Citrix NetScaler Unauthenticated Login Log Command Injection (CVE-2026-88771)), disclosure date 2026-09-27.

• EPSS (probability of exploitation activity in the next 30 days): 1.30%, higher than 70% of all scored CVEs (as of 2026-10-24).
• CVERadar threat level: 57/100 (see methodology).

1. Find every instance. List where citrix netscaler application delivery controller runs, including test, DR and forgotten internet-facing systems, and record the installed version.

   show ns version

2. Upgrade to a fixed release. citrix netscaler application delivery controller: 13.1-64.23 or later; citrix netscaler application delivery controller: 13.1.37.279 or later; citrix netscaler application delivery controller: 14.1-73.37 or later; citrix netscaler gateway: 13.1-64.23 or later. Get the build from the vendor advisory.
3. If you can't patch today, apply the vendor's workaround from the advisory.
4. Verify the fix. Re-run the version check above on every instance and confirm it reports the fixed build (13.1-64.23 or later). Re-scan from outside if the service is exposed.
5. Hunt for signs of earlier compromise. If the system was exposed before you patched, assume it may have been hit and check the items below.
6. Rotate credentials stored on or used by the affected system if you cannot rule out compromise, and keep the logs you reviewed.

Detection hints

• Check the vendor advisory for indicators of compromise and review the affected system's logs back to the disclosure date.

Detection commands are generic starting points, not CVE-specific signatures. Use the indicators from the vendor advisory when it publishes them.

• NVD: CVE-2026-88773 nvd.nist.gov/vuln/detail/CVE-2026-88773
• CVE.org record www.cve.org/CVERecord?id=CVE-2026-88773
• Vendor Advisory support.citrix.com/support-home/kbsearch/article?articleNumber=CTX6970
• FIRST EPSS (2026-10-24) api.first.org/data/v1/epss?cve=CVE-2026-88773