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Vulnerability · Published Sep 27, 2026 · Assigned by NetScaler

CVE-2026-88778TCP Initial Sequence Number (ISN) prediction

High 8.8

In plain English

A high-severity security flaw in ADC from Citrix NetScaler. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 53% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code.

Severity (CVSS 4.0)8.8High
Exploit odds (30 days)0.7%top 46.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack tooling1Public PoC

Official description

Predictable exact value from previous values 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.

Affected products (as reported)

VendorProductVersions
Citrix NetScaler ADC 0 – before 14.1-73.370 – before 13.1-64.230 – before 14.1-73.37 FIPS0 – before 13.1.37.279 FIPS and NDcPP
Citrix NetScaler Gateway 0 – before 14.1-73.370 – before 13.1-64.23

Weakness: CWE-342 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:H/SC:L/SI:L/SA:L

References