Three critical vulnerabilities affect NetScaler ADC and Gateway, including an actively exploited zero-day, CVE-2025-7775, a memory overflow enabling system takeover or denial-of-service. Exploitation requires VPN or remote-access configuration or processing of certain IPv6 web traffic or content routing. CVSS scores are 9.2 for CVE-2025-7775 and 8.8 and 8.7 for two other flaws involving memory handling and inadequate access control. Exploitation cases on unpatched devices have been detected. The Dutch NCSC warns widespread vulnerable configurations increase the likelihood of large-scale abuse and notes parallels with prior CitrixBleed incidents. Immediate installation of updates is strongly advised.
The most alarming vulnerability, CVE-2025-7775, is a memory overflow that allows attackers to take over systems. Or even shut them down completely via a denial-of-service attack. This leak can only be exploited on NetScaler devices that are set up for VPN or remote access, or that process certain IPv6 web traffic or content routing. Citrix has rated its severity at 9.2 on the CVSS scale.
Although exploitation is technically complex, the company warns that a successful attack could have a far-reaching impact on the confidentiality, integrity, and availability of systems. Cases of exploitation on unpatched devices have already been detected. Citrix strongly advises customers to install the available updates immediately. In addition to this zero-day, Citrix has addressed two other vulnerabilities. The first concerns a memory handling error that can lead to unpredictable behavior or a DoS situation.
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