Multiple Citrix NetScaler Flaw Leads to DoS Attack and Data Exposure

Critical vulnerabilities in Citrix NetScaler ADC and NetScaler Gateway have exposed sensitive information and a denial of service attack.

A malicious cyber actor can exploit one of these vulnerabilities to gain control of an affected machine. Citrix has published security upgrades to address the vulnerabilities impacting several products.

Details of the Critical Vulnerabilities

With a CVSS score of 9.4, the vulnerability designated as CVE-2023–4966 is considered highly severe. Without high-level access, user involvement, or tedious processes, the weakness may be remotely exploited.

The appliance must be set up as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or an AAA virtual server to be exposed to attacks.

According to the security bulletin, this vulnerability results in “Sensitive information disclosure.”

The second vulnerability reported is CVE-2023-4967, a high-severity issue with a CVSS score of 8.2, allowing for a ‘Denial of Service attack’ on vulnerable devices.

Affected Versions:

The vulnerabilities impact the following supported versions of NetScaler ADC and NetScaler Gateway: 

• NetScaler ADC and NetScaler Gateway 14.1 before 14.1-8.50
• NetScaler ADC and NetScaler Gateway 13.1 before 13.1-49.15
• NetScaler ADC and NetScaler Gateway 13.0 before 13.0-92.19
• NetScaler ADC 13.1-FIPS before 13.1-37.164
• NetScaler ADC 12.1-FIPS before 12.1-55.300
• NetScaler ADC 12.1-NDcPP before 12.1-55.300

It is noted that NetScaler ADC and NetScaler Gateway version 12.1 are now End-of-Life (EOL) and are vulnerable.

Updated Versions

• NetScaler ADC and NetScaler Gateway 14.1-8.50  and later releases
• NetScaler ADC and NetScaler Gateway  13.1-49.15  and later releases of 13.1
• NetScaler ADC and NetScaler Gateway 13.0-92.19 and later releases of 13.0  
• NetScaler ADC 13.1-FIPS 13.1-37.164 and later releases of 13.1-FIPS  
• NetScaler ADC 12.1-FIPS 12.1-55.300 and later releases of 12.1-FIPS  
• NetScaler ADC 12.1-NDcPP 12.1-55.300 and later releases of 12.1-NDcPP

NetScaler ADC and NetScaler Gateway version 12.1 are now End-of-Life (EOL). Customers are advised to update one of the supported versions to fix the vulnerabilities.

“Cloud Software Group strongly urges affected customers of NetScaler ADC and NetScaler Gateway to install the relevant updated versions of NetScaler ADC and NetScaler Gateway as soon as possible,” reads Citrix’s security bulletin.

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