Citrix NetScaler Authentication Bypass Using an Alternate Path or Channel
CVE-2026-19490 is a critical-severity authentication bypass using an alternate path or channel vulnerability in ADC from NetScaler, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected ADC versions: 14.1 through 73.32; 13.1 through 63.21. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on September 9, 2026, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Update Netscaler Application Delivery Controller to 13.1-37.277 or 13.1-63.21 or 14.1-73.32, whichever matches your release line, or a later version.
- Update Netscaler Gateway to 13.1-63.21 or 14.1-73.32, whichever matches your release line, or a later version.
- CISA's required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
- Read the advisory on support.citrix.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| NetScaler | ADC | 14.1 through 73.32; 13.1 through 63.21 | Not stated |
| NetScaler | Gateway | 14.1 through 73.32; 13.1 through 63.21 | Not stated |
| Citrix | Netscaler Application Delivery Controller | 13.1 up to, but not including, 13.1-37.277; 13.1 up to, but not including, 13.1-63.21; 14.1 up to, but not including, 14.1-73.32; 14.1-66.68 through 14.1-73.32 | 13.1-37.277, 13.1-63.21, 14.1-73.32 |
| Citrix | Netscaler Gateway | 13.1 up to, but not including, 13.1-63.21; 14.1 up to, but not including, 14.1-73.32 | 13.1-63.21, 14.1-73.32 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 9.3 | Critical | CNA |
| CVSS 3.1 | 9.8 | Critical | NVD |
Official description
Vulnerability in NetScaler ADC and NetScaler Gateway. This issue affects ADC: from 14.1 through 73.32 and from 13.1 through 63.21; Gateway: from 14.1 through 73.32 and from 13.1 through 63.21.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Authentication Bypass Using an Alternate Path or Channel
The product requires authentication, but the product has an alternate path or channel that does not require authentication.
How developers prevent this class of flaw
- Funnel all access through a single choke point to simplify how users can access a resource. For every access, perform a check to determine if the user has permissions to access the resource.
More Authentication Bypass Using an Alternate Path or Channel vulnerabilities (CWE-288)
Timeline
- CVE record published.
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: total).
- Deadline for US federal agencies to remediate, set by CISA.
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-19490US Government Resource
Our coverage
Other vulnerabilities in ADC
- 9.5 Critical severity
- 7.5 High severity
- 8.8 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.5 High severity
Recent Authentication Bypass Using an Alternate Path or Channel vulnerabilities
- 7.1 High severity
- 9.1 Critical severity
- 9.8 Critical severity
- 9.1 Critical severity
- 8.1 High severity
- 7.5 High severity
Spotted an error? Tell us.