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CVE-2026-19490 – Authentication Bypass – NetScaler ADC and NetScaler Gateway (13.1 / 14.1)

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Summary

CVE-2026-19490 is a critical authentication bypass vulnerability affecting Citrix NetScaler ADC and NetScaler Gateway, tracked under CWE-288 (Authentication Bypass Using an Alternate Path). It allows a remote, unauthenticated attacker to circumvent authentication controls on appliances configured as a Gateway (SSL VPN, ICA Proxy, CVPN, RDP Proxy) or as an AAA virtual server. The flaw carries a CVSS v4.0 base score of 9.3 (Critical), with no user interaction or privileges required.

Technical details

  • Root cause: an alternate authentication path exists in NetScaler’s Gateway/AAA authentication logic that can bypass standard credential checks.
  • Trigger conditions: the appliance must be configured as a Gateway (SSL VPN, ICA Proxy, CVPN, RDP Proxy) or as an AAA virtual server; on NetScaler 14.1-43.56/13.1-61.28 and later builds, exploitation additionally requires a configured SAML action, while on earlier builds any Gateway/AAA vserver configuration is sufficient.
  • Attack vector: network, exploitable remotely without authentication or user interaction.
  • Impact: full authentication bypass, with high confidentiality, integrity, and availability impact per the CVSS v4.0 vector.
  • As of the advisory date, no public evidence of in-the-wild exploitation has been reported, though internet-facing Citrix Gateway/AAA appliances are historically targeted quickly once details circulate.

Affected software

  • NetScaler ADC: 14.1 from 14.1 up to and including 14.1-73.32; 13.1 from 13.1 up to and including 13.1-63.21
  • NetScaler Gateway: 14.1 from 14.1 up to and including 14.1-73.32; 13.1 from 13.1 up to and including 13.1-63.21
  • NetScaler ADC 14.1-FIPS builds prior to 14.1-73.32 FIPS
  • NetScaler ADC 13.1-FIPS and 13.1-NDcPP builds prior to 13.1-37.277

Severity

CVSS v4.0 Base Score: 9.3 (Critical)
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L
(No CVSS v3.1 score had been published by NVD at the time of this analysis.)

Mitigation and recommended actions

  • Immediate: upgrade to NetScaler ADC and NetScaler Gateway 14.1-73.32 or later, 13.1-63.21 or later, NetScaler ADC 14.1-73.32 FIPS or later, or NetScaler ADC 13.1-37.277 FIPS/NDcPP or later.
  • If patching cannot be performed immediately: review configuration for Gateway (SSL VPN/ICA Proxy/CVPN/RDP Proxy) or AAA virtual server setups and SAML actions to assess exposure, restrict network access to management and authentication interfaces where possible, and prioritize patching as an emergency given the perimeter-facing nature of these appliances.

References

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