GoKawiilCitrix NetScaler zero-day exploited to plant web shells since early September
Mandiant and other security firms say attackers began exploiting an unpatched Citrix NetScaler flaw, tracked as CVE-2026-88772, in early September to install custom web shells and tunneling malware, gain root access, steal credentials, and move into internal networks. Victims span government, financial services, education, legal, and professional services organizations in North America and Europe. Citrix disclosed two related zero-days, CVE-2026-88771 and CVE-2026-88772, on Sunday and released patches after researchers including GreyNoise and watchTowr flagged active exploitation.