Vulnerability identifier: #VU81926

Vulnerability risk: Critical

CVSSv3.1: 9 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L/E:H/RL:O/RC:C]

CVE-ID: CVE-2023-4966

CWE-ID: CWE-119

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
Citrix Netscaler ADC
Client/Desktop applications / Software for system administration
Citrix NetScaler Gateway
Server applications / Application servers

Vendor: Citrix

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to a boundary error. A remote non-authenticated attacker can send specially crafted data to the device, trigger memory corruption and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system but requires that the appliance is configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or as AAAvirtualserver.

Note, the vulnerability is being actively exploited in the wild since August 2023.

Mitigation

Install updates from vendor's website.

For FIPS releases install the following versions:

• NetScaler ADC 13.1-FIPS version 13.1-37.164
• NetScaler ADC 12.1-FIPS version 12.1-55.300
• NetScaler ADC 12.1-NDcPP version 12.1-55.300

Vulnerable software versions

Citrix Netscaler ADC: 12.1-55.289 - 14.1-4.42

Citrix NetScaler Gateway: 12.1-55.289 - 14.1-4.42

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External links
http://support.citrix.com/article/CTX579459
http://www.mandiant.com/resources/blog/remediation-netscaler-adc-gateway-cve-2023-4966

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

Yes. This vulnerability is being exploited in the wild.