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

Citrix NetScaler ADC and NetScaler Gateway contain a buffer overflow vulnerability that allows for sensitive information disclosure when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server.

VendorCitrix
ProductNetScaler ADC and NetScaler Gateway
Date added to KEV2023-10-18
Due date (BOD 22-01)2023-11-08
Known ransomware campaign useKnown
CWECWE-119
Required actionApply mitigations and kill all active and persistent sessions per vendor instructions [https://www.netscaler.com/blog/news/cve-2023-4966-critical-security-update-now-available-for-netscaler-adc-and-netscaler-gateway/] OR discontinue use of the product if mitigations are unavailable.

What to do

  1. Identify every instance of Citrix NetScaler ADC and NetScaler Gateway in your environment (asset inventory, EDR, vulnerability scanner).
  2. Apply CISA's required action: Apply mitigations and kill all active and persistent sessions per vendor instructions [https://www.netscaler.com/blog/news/cve-2023-4966-critical-security-update-now-available-for-netscaler-adc-and-netscaler-gateway/] OR discontinue use of the product if mitigations are unavailable.
  3. Federal civilian agencies must act by 2023-11-08 under BOD 22-01; other organizations can use the same date as a target.
  4. Because ransomware use is known, check for signs of compromise and confirm backups are offline and tested.
  5. Check the vendor advisory and NVD entry linked below for affected versions, then record the fix in your change log.

This CVE is flagged by CISA as known to be used in ransomware campaigns. Rehearse your response before you need it: Ransomware tabletop exercise kit (Runbook Foundry).

Sources

Generated from the CISA feed with AI assistance; facts are taken verbatim from the feed. Not affiliated with or endorsed by CISA. Facts come from the CISA Known Exploited Vulnerabilities catalog (public domain).