CVE-2023-4966: Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability

Vulnerability summary

CVE-2023-4966 is a critical (CVSS 9.4) vulnerability in Citrix NetScaler ADC and NetScaler Gateway. It is known to be exploited: CISA lists it, first on 18-10-2023. It has been used in ransomware campaigns. EPSS estimates a 100.00% chance of exploitation in the next 30 days, higher than 99.9% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 10-10-2023
   PublishedVulnerability first disclosed.
2. 18-10-2023
   Added to CISA KEVCitrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability
3. 08-11-2023
   CISA remediation dueApply mitigations per vendor instructions.
4. 31-07-2026
   Last modifiedVulnerability information updated.

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.

• CWE-119Improper Restriction of Operations within the Bounds of a Memory BufferThe product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.