Description

Citrix has issued fixes for three vulnerabilities in its NetScaler ADC and Gateway products, including a severe zero-day vulnerability with ID CVE-2025-7775 (CVSS 9.2). The vulnerability, which has been seen in the wild, is a memory overflow vulnerability that can result in denial-of-service (DoS) or remote code execution (RCE). The root cause affects Gateway-configured systems, AAA virtual server, or CR virtual server with type HDX, and targets specifically NetScaler instances that are bound with IPv6 services or servers. Citrix confirmed over the weekend that exploitation, which has been seen on unpatched appliances up to August 26, 2025, and emphasized upgrading as imperative since no mitigations are available. As a reaction to the threat, the U.S. Cybersecurity and Infrastructure Security Agency (CISA) promptly listed CVE-2025-7775 in its Known Exploited Vulnerabilities (KEV) list, providing federal agencies only two days (until August 28) to implement the patch, shorter than the usual three-week period covered by Binding Operational Directive 22-01. Although Citrix did not reveal the details of the attacks or offer indicators of compromise (IOCs), the prompt response by CISA emphasizes the gravity and active exploitation of the vulnerability. Organizations are encouraged to make patching a priority to avoid possible breaches or service outages. In addition to CVE-2025-7775, Citrix patched two other high-severity vulnerabilities: CVE-2025-7776 (CVSS 8.8), another memory overflow causing DoS, and CVE-2025-8424 (CVSS 8.7), unauthorized file access through improper access control in the management interface. All three were fixed in NetScaler ADC and Gateway version updates 14.1-47.48, 13.1-59.22, 13.1-FIPS, 13.1-NDcPP, and 12.1-FIPS/12.1-NDcPP. Citrix also took the opportunity to remind users that 12.1 and 13.0 have been officially discontinued, recommending an immediate upgrade to supported releases.