Citrix zero-day vulnerability under attack

Users of Citrix’s NetScaler ADC and NetScaler Gateway (formerly Citrix ADC and Citrix Gateway respectively) appliances should patch as soon as possible, with the vendor announcing a zero-day vulnerability that is under exploitation.

The vulnerabilities only affect customer-managed appliances; Citrix-provided cloud services or Adaptive Authentication services are not affected.

In its advisory, Citrix noted that the most serious vulnerability is CVE-2023-3519, which can be exploited by an unauthenticated attacker to get remote code execution. 

To be vulnerable, the advisory stated, the appliance has to be configured “as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy); or as an AAA virtual server”.

“Exploits of CVE-2023-3519 on unmitigated appliances have been observed”, the advisory stated.

The affected product versions are as follows: NetScaler ADC and NetScaler Gateway 13.1 before 13.1-49.13; NetScaler ADC and NetScaler Gateway 13.0 before 13.0-91.13; NetScaler ADC 13.1-FIPS before 13.1-37.159; NetScaler ADC 12.1-FIPS before 12.1-55.297; and NetScaler ADC 12.1-NDcPP before 12.1-55.297.

NetScaler ADC and Gateway 12.1 is vulnerable, but is end-of-life and won’t be patched.

The other two vulnerabilities are CVE-2023-3466, a reflected cross-site scripting vulnerable that’s only exploitable with victim interaction; and CVE-2023-3467, a privilege escalation bug.

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AndyC

Andy Curtis is an award-winning security consultant, researcher and public speaker. He has been working in the computer security industry since the early 1990s, having been employed by state and federal government, leading healthcare and banking providers across three continents. He has given talks about computer security for some of the world’s largest companies, worked with law enforcement agencies on investigations into hacking groups, and is a regular voice on TV and radio explaining IT security threats.

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