How do I check whether I am affected by CVE-2026-111340?

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.

What is the fix for CVE-2026-111340?

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.

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HIGH8.7CVSS · 50a63c94-1ea7-4568-8c11-eb79e7c5a2b5

NO KNOWN
EXPLOIT

NETSCALER ADC · CVE-2026-111340 · Infrastructure

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

Q: Who is not affected by CVE-2026-111340?

Not affected if: no-email-action, no-kba-ldap-action, no-netscaler.

FIX → 14.1-73.57 · 13.1-64.39 · 14.1-73.58 · 13.1-37.293 ✓ verified

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.

Full story ↓Less ↑

first public Nov 13, 2026 · 2 sources

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01 · Who is affected

✓ Verified Nov 13

Self-managed NetScaler ADC and NetScaler Gateway appliances that have an LDAP authentication action with KBAttribute or an email action configured, on 14.1 or 13.1 builds before the fixed ones. The attack is network-reachable and unauthenticated per Citrix's CVSS vector, and the result is a crash or denial of service. Appliances with neither configuration entry meet no precondition for this CVE.

NetScaler ADC< 14.1-73.57fixed in 14.1-73.57
NetScaler Gateway< 14.1-73.57fixed in 14.1-73.57
NetScaler ADC 13.1< 13.1-64.39fixed in 13.1-64.39
NetScaler Gateway 13.1< 13.1-64.39fixed in 13.1-64.39
NetScaler ADC 14.1-FIPS< 14.1-73.58fixed in 14.1-73.58
NetScaler ADC 13.1-FIPS/NDcPP< 13.1-37.293fixed in 13.1-37.293

Not affected if no-email-action, no-kba-ldap-action, no-netscaler

Who cares authentication, citrix, denial-of-service, gateway, netscaler, self-hosted

Exploited: No reports yet
Public exploit: None on GitHub
EPSS: Not scored
Last updated: Nov 13, 2026

How it unfolded

2 events · Nov 13, 2026 → Nov 13, 2026

Nov 13, 202604:42 UTCNVD CVE-2026-111340
Nov 13, 202604:45 UTCInfraStack Analyst Read Citrix bulletin CTX697305: preconditions, affected/fixed builds, no mitigations. Exploitation not stated. X not checked.

What the sources say, verbatim

178 characters

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.

Sources and references

NVD: CVE-2026-111340Nov 13, 2026
Citrix NetScaler ADC and Gateway Security Bulletin CTX697305Advisory · support.citrix.com

This page as .md · .json · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/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

NVD data is provided by NIST and is public domain. Posts quoted belong to their authors.

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Post Share

HIGH8.7CVSS · 50a63c94-1ea7-4568-8c11-eb79e7c5a2b5

NO KNOWN
EXPLOIT

NETSCALER ADC · CVE-2026-111340 · Infrastructure

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

FIX → 14.1-73.57 · 13.1-64.39 · 14.1-73.58 · 13.1-37.293 ✓ verified

Full story ↓Less ↑

first public Nov 13, 2026 · 2 sources

Check it with your coding agent

It reads this page and tells you if your code or app is affected.

Claude CodeCodexCursorAdd to your agent

01 · Who is affected

✓ Verified Nov 13

NetScaler ADC< 14.1-73.57fixed in 14.1-73.57
NetScaler Gateway< 14.1-73.57fixed in 14.1-73.57
NetScaler ADC 13.1< 13.1-64.39fixed in 13.1-64.39
NetScaler Gateway 13.1< 13.1-64.39fixed in 13.1-64.39
NetScaler ADC 14.1-FIPS< 14.1-73.58fixed in 14.1-73.58
NetScaler ADC 13.1-FIPS/NDcPP< 13.1-37.293fixed in 13.1-37.293

Not affected if no-email-action, no-kba-ldap-action, no-netscaler

Who cares authentication, citrix, denial-of-service, gateway, netscaler, self-hosted

Exploited: No reports yet
Public exploit: None on GitHub
EPSS: Not scored
Last updated: Nov 13, 2026

How it unfolded

2 events · Nov 13, 2026 → Nov 13, 2026

Nov 13, 202604:42 UTCNVD CVE-2026-111340
Nov 13, 202604:45 UTCInfraStack Analyst Read Citrix bulletin CTX697305: preconditions, affected/fixed builds, no mitigations. Exploitation not stated. X not checked.

What the sources say, verbatim

178 characters

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.

Sources and references

NVD: CVE-2026-111340Nov 13, 2026
Citrix NetScaler ADC and Gateway Security Bulletin CTX697305Advisory · support.citrix.com

NVD data is provided by NIST and is public domain. Posts quoted belong to their authors.

Are you affected?

Ask from here. InfraStack checks the affected versions against your stack and answers in your inbox.

InfraStack checks the affected versions against your stack and answers in Slack, with the evidence and the fix.

InfraStack checks it against your stack and answers on your report, with the evidence and the fix.

Run the check

Get the next NetScaler ADC threat the day it hits your stack.

Start free

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

01 · Who is affected

How it unfolded

What the sources say, verbatim

Sources and references

Read next

Get the next NetScaler ADC threat the day it hits your stack.

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

01 · Who is affected

How it unfolded

What the sources say, verbatim

Sources and references

Read next

Get the next NetScaler ADC threat the day it hits your stack.

02 · How to check

03 · The fix