Critical Authentication Bypass and Buffer Overflow Flaws Patched in NetScaler ADC and Gateway

Cloud Software Group disclosed two critical vulnerabilities affecting NetScaler ADC and NetScaler Gateway products. CVE-2026-19490 permits authentication bypass via an alternate path when the appliances operate as SSL VPN, ICA proxy, CVPN, or RDP proxy gateways, or when configured as authentication, authorization, and auditing virtual servers. CVE-2026-19489 is a buffer overflow in LSN groups with SIP ALG enabled that can lead to unexpected behavior or denial of service. Both issues received CVSS v4.0 base scores of 9.3 and 8.8 respectively. Fixed builds 14.1-73.32 and 13.1-63.21 are now available along with corresponding FIPS and NDcPP updates.

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Cloud Software Group has released a security advisory detailing two severe vulnerabilities in NetScaler ADC (formerly Citrix ADC) and NetScaler Gateway (formerly Citrix Gateway). The issues are rated Critical, the highest severity level, prompting immediate calls for customers to apply updates.

CVE-2026-19490 allows attackers to bypass authentication by leveraging an alternate path. The flaw affects environments where the products function as SSL VPN, ICA proxy, CVPN, or RDP proxy gateways, as well as when configured as authentication, authorization, and auditing virtual servers. In certain builds, the presence of a configured SAML action is also a prerequisite for exploitation.

CVE-2026-19489 is a buffer overflow vulnerability that manifests when SIP ALG is enabled within an LSN group. Successful exploitation may result in unexpected behavior or a denial-of-service condition.

The CVSS v4.0 base scores are 9.3 for CVE-2026-19490 and 8.8 for CVE-2026-19489. The advisory contains no information indicating that the vulnerabilities have been exploited in the wild.

Patches are available in builds 14.1-73.32 and 13.1-63.21. Corresponding updates for FIPS and NDcPP editions have also been released, and administrators are strongly advised to upgrade without delay.

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