CVE-2023-4966

What this means for your business

• It affects Citrix NetScaler ADC and NetScaler Gateway. It matters if your company, or a supplier that handles your data, runs it.
• Attackers are already using it. CISA added it to its list of flaws used in real attacks on 18 October 2023.
• Ransomware gangs are known to have used it.
• FIRST's prediction model gives it a 100% chance of attack attempts being seen in the next 30 days, ranking above 99% of all known flaws.

What to do

1. 1Check whether your company or your suppliers run Citrix NetScaler ADC and NetScaler Gateway.
2. 2If you do, follow CISA's required action below. No patch reference has been published yet.
3. 3Treat it as urgent. US federal agencies must fix it by 8 November 2023. That deadline does not apply to private companies, but it shows how seriously CISA takes it.
4. 4Because attackers have used it, check the affected systems for signs of a break-in, not only for the update.