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CVE-2026-88776 – Memory Overflow / Denial-of-Service – Citrix NetScaler ADC and Gateway (Oracle Load

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Summary

CVE-2026-88776 is a memory overflow vulnerability in Citrix NetScaler ADC and NetScaler Gateway that can cause unpredictable or erroneous appliance behavior or a Denial of Service. The flaw affects load balancing virtual servers configured with a service type of Oracle, and carries a CVSS score of 8.8 (High). It was disclosed by Citrix on September 27, 2026 as part of a broader security bulletin that also addressed two actively exploited zero-day remote code execution vulnerabilities.

Technical details

  • Root cause: A memory overflow condition in the NetScaler packet-processing logic for load balancing virtual servers.
  • Trigger conditions: The vulnerability requires the appliance to have a load balancing virtual server configured with service type Oracle; appliances without this configuration are not affected.
  • Attack vector: Network-based; no authentication or user interaction is required to reach the vulnerable code path.
  • Impact: Successful exploitation can cause unpredictable or erroneous appliance behavior or a Denial of Service, disrupting availability of load-balanced services.

Affected software

  • Citrix NetScaler ADC and NetScaler Gateway before 14.1-73.37
  • Citrix NetScaler ADC and NetScaler Gateway before 13.1-64.23
  • Citrix NetScaler ADC 14.1-73.37 FIPS and NDcPP
  • Citrix NetScaler ADC 13.1-37.279 FIPS and NDcPP

Severity

CVSS Score: 8.8 (High)
CVSS 4.0 Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N

Mitigation and recommended actions

  • Immediate: Upgrade Citrix NetScaler ADC and NetScaler Gateway to 14.1-73.37, 13.1-64.23, 14.1-73.37 FIPS, or 13.1.37.279 FIPS/NDcPP or later, as applicable to the deployed branch.
  • If no patch can be applied immediately: Restrict or disable load balancing virtual servers configured with service type Oracle until the update can be applied, and limit network exposure of NetScaler management and virtual server interfaces to trusted networks only. Review Citrix’s advisory for the latest guidance, as no formal workaround beyond upgrading has been published for this specific CVE.

References

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