Hackers Exploit Two Critical Citrix NetScaler Zero-Days to Deploy Web Shells and Enable Lateral Movement
Two critical zero-day vulnerabilities in Citrix NetScaler, tracked as CVE-2026-88771 and CVE-2026-88772, are being actively exploited in the wild to achieve unauthenticated remote code execution. Attackers deploy password-protected PHP web shells such as WHIPSHOT and use the Python-based SLAPSHOT tunneling tool for lateral movement inside targeted networks. The flaws affect NetScaler ADC and NetScaler Gateway appliances with default configurations, and one requires DTLS enabled on VPN vServers. Citrix has released patches for versions 13.1-64.23 and 14.1-73.37, while CISA added the issues to its KEV catalog with a September 30, 2026 remediation deadline for U.S. federal agencies. Organizations are advised to hunt for indicators including modified httpd.conf entries, anomalous setuid permissions on /bin/sh, and suspicious files in /var/netscaler/logon/LogonPoint/custom before applying updates.
HispasecSep 30, 2026Translated from Spanish