CVE entry · CVE-2026-19490
CVE-2026-19490: Citrix NetScaler Authentication Bypass Using an Alternate Path or Channel Vulnerability
Citrix NetScaler ADC and NetScaler Gateway contain an authentication-bypass vulnerability involving an alternate path or channel. When the NetScaler appliance is configured as an AAA virtual server or as a Gateway (SSL VPN, ICA Proxy, CVPN, or RDP Proxy), an unauthenticated remote threat actor may be able to bypass authentication.
- Actively exploited: added to CISA’s KEV catalog on September 9, 2026.
- Use by ransomware: not established so far.
- Remediation deadline for US federal agencies: September 12, 2026.
Description from CISA’s KEV catalog.
What to do
- Check whether your estate includes Citrix NetScaler, including internet-facing devices.
- Apply the vendor’s patch or mitigations (references below). Failing that, isolate the product or stop using it, as CISA requires of US federal agencies.
- An exploited vulnerability has often been used before it was fixed: look for signs of compromise, especially on internet-facing devices.
References
- Vendor advisory or reference cited by CISA (support.citrix.com)
- NVD entry (NIST)
- CISA KEV catalog
Other Citrix vulnerabilities
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Citrix NetScaler Improper Restriction of Operations within the Bounds of a Memory Buffer Vulnerability
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Citrix NetScaler Improper Restriction of Operations within the Bounds of a Memory Buffer Vulnerability
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Citrix NetScaler Improper Input Validation Vulnerability
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Citrix NetScaler ADC and NetScaler Gateway Improper Restriction of Operations within the Bounds of a Memory Buffer Vulnerability
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Citrix NetScaler Out-of-Bounds Read Vulnerability
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Citrix NetScaler Memory Overflow Vulnerability