Description of Problem
Two vulnerabilities have been discovered in NetScaler ADC (formerly Citrix ADC) and NetScaler Gateway (formerly Citrix Gateway). Refer below for further details.
NetScaler are affected is RDP-Proxy Feature is enabled and/or Kerberos Constrained Delegation is configured!
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 14.1-29.72
- NetScaler ADC and NetScaler Gateway 13.1 BEFORE 13.1-55.34
- NetScaler ADC 13.1-FIPS BEFORE 13.1-37.207
- NetScaler ADC 12.1-FIPS BEFORE 12.1-55.321
- NetScaler ADC 12.1-NDcPP BEFORE 12.1-55.321
Note: NetScaler ADC and NetScaler Gateway versions 12.1 and 13.0 are now End Of Life (EOL) and are vulnerable. Customers are recommended to upgrade their appliances to one of the supported versions that address the vulnerabilities.
This bulletin only applies to customer-managed NetScaler ADC and NetScaler Gateway. Customers using Citrix-managed cloud services or Citrix-managed Adaptive Authentication do not need to take any action.
Summary
NetScaler ADC and NetScaler Gateway contain the vulnerabilities mentioned below
| CVE ID | Description | Pre-requisites | CWE | CVSS |
| CVE-2024-8534 | Memory safety vulnerability leading to memory corruption and Denial of Service | The appliance must be configured as a Gateway (VPN Vserver) with RDP Feature enabled ORThe appliance must be configured as a Gateway (VPN Vserver) and RDP Proxy Server Profile is created and set to Gateway (VPN Vserver) ORThe appliance must be configured as a Auth Server (AAA Vserver) with RDP Feature enabled | CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer | CVSS v4.0 Base Score: 8.4(CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:H/SC:N/SI:N/SA:L) |
| CVE-2024-8535 | Authenticated user can access unintended user capabilities | The appliance must be configured as a Gateway (SSL VPN, ICA Proxy, CVPN, RDP Proxy) with KCDAccount configuration for Kerberos SSO to access backend resourcesOR The appliance must be configured as aAuth Server (AAA Vserver) with KCDAccount configuration for Kerberos SSO to access backend resources | CWE-440: Expected Behavior Violation | CVSS v4.0 Base Score: 5.8(CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:H/SI:H/SA:H) |
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 14.1-29.72 and later releases
- NetScaler ADC and NetScaler Gateway 13.1-55.34 and later releases of 13.1
- NetScaler ADC 13.1-FIPS 13.1-37.207 and later releases of 13.1-FIPS
- NetScaler ADC 12.1-FIPS 12.1-55.321 and later releases of 12.1-FIPS
- NetScaler ADC 12.1-NDcPP 12.1-55.321 and later releases of 12.1-NDcPP
Note: NetScaler ADC and NetScaler Gateway versions 12.1 and 13.0 are now End Of Life (EOL) and no longer supported. Customers are recommended to upgrade their appliances to one of the supported versions that address the vulnerabilities.
CVE-2024-8534:
Customers can determine if they have an appliance configured as one of the following by inspecting their ns.conf file for the specified strings
- A Gateway (VPN Vserver) with the RDP Feature enabled,
enable ns feature.*rdpproxyadd vpn vserver - A Gateway (VPN Vserver) with an RDP Proxy Server Profile created and set to the Gateway (VPN Vserver)
add rdp serverprofile <RDP_server_name>add vpn vserver <vserver_name> -rdpServerProfileName <RDP_server_name> - An Auth Server (AAA Vserver) with the RDP Feature enabled.
enable ns feature.*rdpproxyadd authentication vserver
CVE-2024-8535:
Customers can determine if they have an appliance configured as one of the following by inspecting their ns.conf file for the specified strings
- A Gateway (SSL VPN, ICA Proxy, CVPN, RDP Proxy) with KCDAccount configuration for Kerberos SSO to access backend resources
add aaa kcdaccount - An Auth Server (AAA Vserver) with KCDAccount configuration for Kerberos SSO to access backend resources
add aaa kcdaccount
In addition, upon upgrading to the fixed version, customers must perform the shell commands mentioned below:nsapimgr_wr.sh -ys call=ns_aaa_flush_kerberos_tickets
Note: In case of High Availability (HA) or Cluster setup of the NetScaler appliances, the above operation should be performed after upgrading all the appliances.