A critical vulnerability, designated as CVE-2025-7775, is being exploited in Citrix NetScaler devices. The vulnerability is a zero-day remote code execution flaw that is under active exploitation, with multiple outlets reporting that it affects a large number of devices. However, there is some uncertainty as reports also mention other vulnerabilities, including CVE-2025-6543, and a separate issue affecting Cisco email security appliances, which may or may not be related to the CVE-2025-7775 vulnerability.