CVE-2023-4966 Citrix Bleed: Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow
Unauthenticated attackers can disclose sensitive session data from Citrix NetScaler ADC and Gateway when configured as a Gateway or AAA virtual server.
- Exploited in the wild
- Since 18 Oct 2023
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2023-4966?
CVE-2023-4966 (Citrix Bleed) is a critical vulnerability in Citrix NetScaler ADC, published on 10 Oct 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Sensitive information disclosure in NetScaler ADC and NetScaler Gateway when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server.
Weakness: CWE-119
Which versions are affected by CVE-2023-4966?
It affects 2 products.
Products include Citrix NetScaler ADC, Citrix Netscaler Gateway.
How do I fix CVE-2023-4966?
No fix has been published for CVE-2023-4966 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 8 Nov 2023.
Is CVE-2023-4966 being exploited?
Yes. Attackers have exploited CVE-2023-4966 in the wild since at least 18 Oct 2023, including in ransomware campaigns.
Public exploit code: 1 Metasploit module, 1 Nuclei template and 14 proofs of concept on GitHub.
Other vulnerabilities in Citrix NetScaler ADC
- CVE-2023-3519 Citrix NetScaler ADC and NetScaler Gateway Code Injection
- CVE-2026-88771 Citrix NetScaler Improper Input Validation
- CVE-2026-88772 Citrix NetScaler Improper Restriction of Operations within the Bounds of a Memory Buffer
- CVE-2026-19490 Citrix NetScaler Authentication Bypass Using an Alternate Path or Channel
- CVE-2026-3055 Citrix NetScaler Out-of-Bounds Read
Sources
Also known as GHSA-2g42-2pwg-93cj.