CVE-2026-88772: Citrix NetScaler Improper Restriction of Operations within the Bounds of a Memory Buffer Vulnerability

In short

Citrix NetScaler has a weakness classified as improper restriction of operations within the bounds of a memory buffer (CWE-119). CISA added it to its Known Exploited Vulnerabilities catalog on 2026-09-27. NVD lists CVSS 4.0 at 9.5 CRITICAL.

What it is

“Citrix NetScaler ADC and NetScaler Gateway contain an improper restriction of operations within the bounds of a memory buffer vulnerability that could allow for remote code execution or denial of service” — CISA KEV, retrieved 2026-11-01

“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 Remote Code Execution or Denial of Service” — NVD, retrieved 2026-11-01

Who is affected

Citrix NetScaler. NVD lists the following versions as affected:

• Citrix Netscaler Application Delivery Controller: from 13.1 inclusive, before 13.1-64.23
• Citrix Netscaler Application Delivery Controller: from 13.1 inclusive, before 13.1.37.279
• Citrix Netscaler Application Delivery Controller: from 14.1 inclusive, before 14.1-73.37
• Citrix Netscaler Application Delivery Controller: from 14.1-66.68 inclusive, through 14.1-73.37
• Citrix Netscaler Gateway: from 13.1 inclusive, before 13.1-64.23
• Citrix Netscaler Gateway: from 14.1 inclusive, before 14.1-73.37

Exploitation status

CISA KEV added: 2026-09-27. Known ransomware campaign use: Not reported by CISA. Due date CISA set for US federal civilian agencies: 2026-09-30.

Scores

NVD CVSS 4.0: 9.5 CRITICAL; vector CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source 50a63c94-1ea7-4568-8c11-eb79e7c5a2b5.

EPSS by FIRST: 78.16%; percentile 99.58; score date 2026-10-31. EPSS estimates the probability of exploitation in the next 30 days.

CWE: CWE-119.

Timeline

CISA required action

“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 each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.” — CISA KEV

What to do

• Confirm whether you run Citrix NetScaler and which version.
• Apply the vendor update or mitigation in the advisory.
• Follow CISA’s required action.
• Review the vendor guidance on signs of compromise.
• Track the fix through completion.

References

• Vendor Advisory: https://support.citrix.com/support-home/kbsearch/article?articleNumber=CTX697096&articleTitle=Citrix_NetScaler_ADC_and_Citrix_NetScaler_Gateway_Security_Bulletin_for_CVE_2026_88771_CVE_2026_88772_CVE_2026_88773_CVE_2026_88774_CVE_2026_88775_CVE_2026_88776_CVE_2026_88777_and_CVE_2026_88778
• NVD detail
• CVE.org record
• CISA KEV catalog

Sources and dates

CISA Known Exploited Vulnerabilities Catalog, version 2026.10.30; retrieved 2026-11-01. CISA KEV data: CC0 1.0. No endorsement by CISA.

NVD retrieved: 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.

EPSS scores by FIRST; score date 2026-10-31.