---
id: "CVE-2026-111340"
page: "https://infrastack.ai/live/CVE-2026-111340"
kind: "vulnerability"
aliases: ["CVE-2026-111340"]
title: "Citrix NetScaler: memory overflow in KBA authentication enables denial of service"
severity: "high"
cvss: 8.7
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: [{"name": "NetScaler ADC", "fixed": ["14.1-73.57"], "affected": "< 14.1-73.57", "ecosystem": "vendor"}, {"name": "NetScaler Gateway", "fixed": ["14.1-73.57"], "affected": "< 14.1-73.57", "ecosystem": "vendor"}, {"name": "NetScaler ADC 13.1", "fixed": ["13.1-64.39"], "affected": "< 13.1-64.39", "ecosystem": "vendor"}, {"name": "NetScaler Gateway 13.1", "fixed": ["13.1-64.39"], "affected": "< 13.1-64.39", "ecosystem": "vendor"}, {"name": "NetScaler ADC 14.1-FIPS", "fixed": ["14.1-73.58"], "affected": "< 14.1-73.58", "ecosystem": "vendor"}, {"name": "NetScaler ADC 13.1-FIPS/NDcPP", "fixed": ["13.1-37.293"], "affected": "< 13.1-37.293", "ecosystem": "vendor"}]
ecosystems: []
tags: ["authentication", "citrix", "denial-of-service", "gateway", "infrastructure", "netscaler", "self-hosted"]
not_affected_if: ["no-email-action", "no-kba-ldap-action", "no-netscaler"]
published_at: "2026-11-13T04:17:36+00:00"
first_seen_at: "2026-11-13T04:42:39+00:00"
updated_at: "2026-11-13T04:45:16+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-111340", "first_seen_at": "2026-11-13T04:42:39+00:00"}, {"source": "analyst", "url": "https://support.citrix.com/external/article/CTX697305", "first_seen_at": "2026-11-13T04:45:16+00:00", "cites": ["https://support.citrix.com/external/article/CTX697305"]}]
exploit_sources: []
---

# Citrix NetScaler: memory overflow in KBA authentication enables denial of service

Link for people: https://infrastack.ai/live/CVE-2026-111340 (this .md is for agents)

A stack-based buffer overflow (CWE-121) in NetScaler's knowledge-based authentication (KBA) can cause unpredictable behavior or denial of service. Citrix rates it CVSS v4 8.7 with no authentication or user interaction needed (AV:N/PR:N); the impact scored is availability only. It applies only if the appliance has an LDAP action with KBAttribute or an Email action configured. The bulletin does not report exploitation.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:NetScaler ADC affected < 14.1-73.57 fixed 14.1-73.57
- vendor:NetScaler Gateway affected < 14.1-73.57 fixed 14.1-73.57
- vendor:NetScaler ADC 13.1 affected < 13.1-64.39 fixed 13.1-64.39
- vendor:NetScaler Gateway 13.1 affected < 13.1-64.39 fixed 13.1-64.39
- vendor:NetScaler ADC 14.1-FIPS affected < 14.1-73.58 fixed 14.1-73.58
- vendor:NetScaler ADC 13.1-FIPS/NDcPP affected < 13.1-37.293 fixed 13.1-37.293

## How to check

Search the NetScaler running config for lines matching 'add authentication ldapAction .* -KBAttribute .*' or 'add authentication emailAction .*'. If neither exists, the precondition is not met. Then check the firmware version (show ns version) against: 14.1 before 14.1-73.57, 13.1 before 13.1-64.39, 14.1-FIPS before 14.1-73.58, 13.1-FIPS/NDcPP before 13.1-37.293.

## Fix

Upgrade to 14.1-73.57 or later, 13.1-64.39 or later 13.1, 14.1-FIPS 14.1-73.58 or later, or 13.1-FIPS/13.1-NDcPP 13.1-37.293 or later. Citrix lists no workaround or mitigation.

## Timeline

- 2026-11-13T04:42:39+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-111340
- 2026-11-13T04:45:16+00:00 analyst https://support.citrix.com/external/article/CTX697305 — Read Citrix bulletin CTX697305: preconditions, affected/fixed builds, no mitigations. Exploitation not stated. X not checked.

## Documents

- [advisory] Citrix NetScaler ADC and Gateway Security Bulletin CTX697305 https://support.citrix.com/external/article/CTX697305

## From the sources

Memory overflow in KBA (knowledge-based authentication) can lead to unpredictable or erroneous behavior or Denial of Service in Citrix NetScaler ADC and Citrix NetScaler Gateway.

---

_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_