US, Australia warn of latest Citrix vulnerability after NetScaler advisory

A new vulnerability is giving cybercriminals the ability to crash Citrix NetScaler appliances, prompting urgent warnings from multiple government agencies.

Customers began reporting strange exploitation incidents on Friday, even on appliances that were up to date on all patches. 

Citrix confirmed late on Friday that it was “tracking a newly observed issue” related to some customer-managed NetScaler deployments but claimed the problem was not connected to vulnerabilities reported last week that also caused alarm among cybersecurity experts.

By Saturday evening, Citrix released a security advisory and a blog addressing the vulnerability, tagging it as CVE-2026-88779. On Sunday, the Cybersecurity and Infrastructure Security Agency (CISA) ordered all federal agencies to patch the bug by Wednesday and conduct forensic triage. 

Citrix NetScaler application delivery controllers (ADC) and Gateway devices are used by large organizations to manage traffic and authentication.

The…