Citrix hat für NetScaler 2 neue CVEs (Base Score: 9.3) veröffentlicht. Die Severity wurde als «Kritisch» eingestuft. Es sind alle NetScaler mit AAA und Gateway in Version 13.1 und 14.1 betroffen.
Multiple vulnerabilities have been discovered in NetScaler ADC (formerly Citrix ADC) and NetScaler Gateway (formerly Citrix Gateway). Refer below for further details.
Affected Versions:
The following supported versions of NetScaler ADC and NetScaler Gateway are affected by the vulnerabilities:
NetScaler ADC and NetScaler Gateway 14.1 BEFORE 14.1-73.32
NetScaler ADC and NetScaler Gateway 13.1 BEFORE 13.1-63.21
NetScaler ADC FIPS BEFORE 14.1-73.32 FIPS
NetScaler ADC FIPS and NDcPP BEFORE 13.1-37.277
Additional Note: Secure Private Access Hybrid deployments using NetScaler instances are also affected by the vulnerabilities. Customers need to upgrade these NetScaler instances to the recommended NetScaler builds to address the vulnerabilities.
This bulletin only applies to customer-managed NetScaler ADC and NetScaler Gateway. Cloud Software Group upgrades the Citrix-managed cloud services and Citrix-managed Adaptive Authentication with the necessary software updates.
Summary:
NetScaler ADC and NetScaler Gateway are affected by the vulnerabilities mentioned below
CVE-ID
Description
Pre-conditions
CWE
CVSSv4
CVE-2026-19489
Memory overflow vulnerability leading to unpredictable behavior or Denial of Service
SIP ALG(Session Initiation Protocol Application Layer Gateway) should be enabled on a Large Scale NAT (LSN) group configuration.
CWE-119 – Improper Restriction of Operations within the Bounds of a Memory Buffer
CVSS v4.0 Base Score: 8.8(CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:L)
CVE-2026-19490
Authentication bypass using an alternate path
The appliance must be configured as a Gateway (SSL VPN, ICA Proxy, CVPN, RDP Proxy) or an AAA virtual server, subject to the following version-specific requirements:14.1-43.56 or later: Applicable only when configured with a SAML action.
14.1-43.55 or earlier: Applicable when configured with Gateway (SSL VPN, ICA Proxy, CVPN, RDP Proxy ) or AAA vserver
13.1-61.28 or later: Applicable only when configured with a SAML action.
13.1-61.27 or earlier: Applicable when configured with Gateway (SSL VPN, ICA Proxy, CVPN, RDP Proxy) or AAA vserver
13.1 FIPS: Applicable when configured with Gateway (SSL VPN, ICA Proxy, CVPN, RDP Proxy) or AAA vserver.
CWE-288: Authentication Bypass Using an Alternate Path
CVSS v4.0 Base Score: 9.3(CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L)
What Customers Should Do
Cloud Software Group strongly urges affected customers of NetScaler ADC and NetScaler Gateway to install the relevant updated versions as soon as possible.
NetScaler ADC and NetScaler Gateway 14.1-73.32 and later releases
NetScaler ADC and NetScaler Gateway 13.1-63.21 and later releases of 13.1
NetScaler ADC 14.1-FIPS 14.1-73.32 FIPS and later releases of 14.1-FIPS
NetScaler ADC 13.1-FIPS and 13.1-NDcPP 13.1-37.277 and later releases of 13.1-FIPS and 13.1-NDcPP
Steps to determine if an appliance meets the CVE preconditions
For CVE-2026-19489:
Customers can determine if the appliance meets the precondition by inspecting their NetScaler configuration for the specified string:
«add lsn group.*sipalg.*»
For CVE-2026-19490:
Customers can determine if the appliance meets the precondition by inspecting their NetScaler configuration for the specified string:
An issue has been identified in the XenServer management API SDK that may allow an attacker on the management network who is able to intercept specific HTTPS requests within a higher-level operation to be able to act with the privileges of the intercepted administrator. This issue affects the XenCenter management agent together with third-party PowerShell and C# SDK clients.
This issue has the following identifier:
CVE-2026-42491
Affected Versions
This issue affects XenCenter versions before 2026.4.0 and, for PowerShell and C# clients only, SDK versions before 26.15.0. As the issue is in the client-side (XenCenter and SDK) code, it is independent of the version of XenServer that is in use.
Vulnerabilities have been discovered in the Citrix Secure Access Client for Windows and Citrix Endpoint Analysis Client. Refer to the information below for further details:
Affected Versions:
The following supported versions of Citrix Secure Access Client for Windows and Citrix Endpoint Analysis Client for Windows are affected by CVE-2026-53565:
Citrix Secure Access Client for Windows versions BEFORE 26.6.1.20
Citrix Endpoint Analysis Client for Windows versions BEFORE 26.5.1.7
The following supported versions of Citrix Secure Access Client for Windows are affected by CVE-2026-53566:
Citrix Secure Access Client for Windows versions BEFORE 26.6.1.20
Details
Citrix Secure Access Client for Windows and Citrix Endpoint Analysis Client for Windows contain the vulnerabilities mentioned below
CVE-ID
Description
Affected Products
Pre-conditions
CWE
CVSSv4
CVE-2026-53565
Local Privilege escalation allows a low-privileged user to gain SYSTEM privileges
Citrix Secure Access Client for Windows AND Citrix Endpoint Analysis Client for Windows
Standard user access on local system
CWE-269: Improper Privilege Management
CVSS v4.0 Base Score: 8.5(CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N)
CVE-2026-53566
Out-of-bounds memory read
Citrix Secure Access Client for Windows
Standard user access on local system and DNE driver is not installed
CWE-125: Out-of-bounds Read
CVSS v4.0 Base Score: 6.8 CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
What Customers Should Do
Cloud Software Group strongly urges customers of Citrix Secure Access Client for Windows and Citrix Endpoint Analysis Client to install the relevant updated versions as soon as possible:
Citrix Secure Access Client for Windows 26.6.1.20 and later releases
Citrix Endpoint Analysis Client for Windows 26.5.1.7 and later releases
Steps to determine if an appliance meets the CVE preconditions
Kunden, die auf ihrem NetScaler Kerberos für SSO PreAuthentication verwenden, bekommen nach dem Microsoft April Update ein Problem. Kerberos Negogiate (SSO) funktioniert danach nicht mehr mit dem NetScaler und auch weitere Umsysteme können davon betroffen sein. Sie erhalten bei einem Login Versuch via NetScaler folgenden Eintrag im ns.log:
default AAATM Message 97485 0 : "NS kerberos: Failed to verifiy negotiate data with errcode 983044"
Umgemünzt auf den NetScaler bedeutet dies dass der Wert 1, temporär wieder RC4 Kerberos Ticket für Netscaler SPNs erlaubt. Nach dem RegKey verändern ist ein gestaffelter DC reboot erforderlich!
ACHTUNG: Diese Anpassungen sind nur als Workaround zu verstehen und sollten wieder rückgängig gemacht werden, sobald Citrix einen Fix für den Fehler bereitstellt!
Update 08.05.2026 – Problemlösung
Allgemeine Voraussetzung
Der zugehörige AD Service Account muss AES 125 bit und oder AES 256 bit erlauben
Danach das KeyTab File neu erzeugen und KeyTab File am Netscaler ersetzen. Ganz wichtig dabei ist die Grossschreibung!
Attention! Please note the following regarding to this update:
Customers who already have transitioned to Netscaler LAS can upgrade without any special remarks. If you have not yet changed the Licensing mode, please check the requirements for LAS prior to the update!
Upgrading without proper LAS activation can lead to licensing issues. While these can be resolved by downloading a new file-based license, this workaround is only available until April 15, 2026.
Severity – Critical
Description of Problem
Vulnerabilities have been discovered in NetScaler ADC (formerly Citrix ADC) and NetScaler Gateway (formerly Citrix Gateway). Refer below for further details.
Affected Versions:
The following supported versions of NetScaler ADC and NetScaler Gateway are affected by the vulnerabilities:
CVE-2026-3055:
NetScaler ADC and NetScaler Gateway 14.1 BEFORE 14.1-66.59
NetScaler ADC and NetScaler Gateway 13.1 BEFORE 13.1-62.23
NetScaler ADC FIPS and NDcPP BEFORE 13.1-37.262
CVE-2026-4368:
NetScaler ADC and NetScaler Gateway 14.1-66.54
Note: This bulletin only applies to customer-managed NetScaler ADC and NetScaler Gateway. Cloud Software Group upgrades Citrix-managed cloud services and Citrix-managed Adaptive Authentication with the necessary software updates.
Details
NetScaler ADC and NetScaler Gateway are affected by the vulnerabilities mentioned below:
CVE-ID
Description
Pre-conditions
CWE
CVSS v4.0
CVE-2026-3055
Insufficient input validation leading to memory overread
Citrix ADC or Citrix Gateway must be configured as a SAML IDP
CWE-125: Out-of-bounds Read
CVSS v4.0 Base Score: 9.3(CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L)
CVE-2026-4368
Race Condition leading to User Session Mixup
Appliance must be configured as:Gateway (SSL VPN, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server
CWE-362: Race Condition
CVSS v4.0 Base Score: 7.7(CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N)
What Customers Should Do
CVE 2026-3055 was identified internally through our ongoing security reviews and broader efforts to strengthen the security of the product.
Cloud Software Group strongly urges affected customers of NetScaler ADC and NetScaler Gateway to install the relevant updated versions as soon as possible.
NetScaler ADC and NetScaler Gateway 14.1-66.59 and later releases
NetScaler ADC and NetScaler Gateway 13.1-62.23 and later releases of 13.1
NetScaler ADC 13.1-FIPS and 13.1-NDcPP 13.1.37.262 and later releases of 13.1-FIPS and 13.1-NDcPP
Note: Customers are recommended to upgrade their appliances to one of the supported versions that address the vulnerabilities.
CVE-2026-3055 :
Customers can determine if they have an appliance configured as a SAML IDP Profile by inspecting their NetScaler Configuration for the specified string:
add authentication samlIdPProfile .*
CVE-2026-4368
Customers can determine if they have an appliance configured as one of the following by inspecting their NetScaler Configuration for the specified strings
An Auth Server (AAA Vserver):
add authentication vserver .*
A Gateway (VPN Vserver, ICA Proxy, CVPN, RDP Proxy) :
