VULNpocalypse

CVE-2026-19490: Citrix NetScaler Authentication Bypass Using an Alternate Path or Channel Vulnerability

Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.

Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.

What it is

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.

Description quoted from the CVE record (assigned by NetScaler, published 2026-08-19).

Weakness: CWE-288 Authentication Bypass Using an Alternate Path or Channel

How it can be exploited

Exploitable over the network with low attack complexity with no special attack requirements needing no privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. 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

CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: yes. Technical impact: total.

On CISA KEV since
2026-09-09
US federal deadline
2026-09-12
Ransomware use
Not known

Public exploit evidence (Exploit Observer)

Also known as: BDU:2026-14208, EUVD-2026-62395, GHSA-7c6h-rhhv-wm8r

VEDAS cluster: VEDAS:FRESHFJORD

Exploit Observer links 5 pieces of public exploit code or detection modules that name this CVE or one of its aliases.

Exploit code and modules (5)

Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.

Research and write-ups (4)

Vulnerability databases and vendor advisories (4)

Catalogue entries, not exploit evidence.

News (1)

109 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.

VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.

Live scores

EPSS
0.327
likely to be attacked soon
VEDAS
0.981
strong exploit evidence
On CISA KEV
Yes, since 2026-09-09
Detection rule
Nuclei
EPSS (chance of attack)
100.1Added to CISA KEV 2026-09-09CVE-2026-19490 EPSS over time2026-082026-11-01
VEDAS (exploit evidence)
100.9Added to CISA KEV 2026-09-09CVE-2026-19490 VEDAS over time2026-082026-11-01

Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish. The vertical line is the day CISA added it to its exploited list.

VEDAS flagged this bug about 19 days before CISA confirmed attacks.

Who is affected

ProductAffectedNot affected
NetScaler ADCfrom 14.1 up to and including 73.32
from 13.1 up to and including 63.21		Not stated
NetScaler Gatewayfrom 14.1 up to and including 73.32
from 13.1 up to and including 63.21		Not stated

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

Exploit Observer also maps it to: citrix netscaler_application_delivery_controller, citrix netscaler_gateway, citrix_systems_inc. netscaler_adc, citrix_systems_inc. netscaler_gateway.

How to fix it

CISA 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.

Vendor guidance:

How to detect it

Nuclei template (active check)

Citrix NetScaler ADC/Gateway - SAML Authentication Bypass

Citrix NetScaler ADC and NetScaler Gateway (ADC/Gateway 14.1 before 73.32 and 13.1 before 63.21), when a SAML Gateway or AAA virtual server is configured, mishandle RelayState/SAMLResponse processing in /cgi/samlauth, letting an unauthenticated attacker bypass authentication and reach post-login code (“created session for anonymous”). The flaw is actively exploited (CISA KEV). The template distinguishes a vulnerable build from a patched one differentially: a probe whose RelayState decodes to the 20-byte “ctx=” + NUL marker reaches the unguarded path and returns HTTP 500 with the NetScaler internal error 43524, while an equal-length control RelayState is rejected earlier and returns HTTP 200 “Malformed Assertion”. A patched appliance returns the 200 “Malformed Assertion” for the probe too, so only the differing pair confirms the bypass.

Name and description quoted from the template, written by VEDAS.

The template sends 2 requests (POST /cgi/samlauth, POST /cgi/samlauth); it decides using dsl matchers. Severity in the template: critical. Marked as not yet verified against a live vulnerable target.

Run it against a host you own or are authorised to test:

bash
nuclei -u https://your-host -t CVE-2026-19490.yaml
Show the template (55 lines)
yaml
id: CVE-2026-19490

info:
  name: "Citrix NetScaler ADC/Gateway - SAML Authentication Bypass"
  author: vedas-arpsyndicate
  severity: critical
  description: |
    Citrix NetScaler ADC and NetScaler Gateway (ADC/Gateway 14.1 before 73.32 and 13.1 before 63.21), when a
    SAML Gateway or AAA virtual server is configured, mishandle RelayState/SAMLResponse processing in
    /cgi/samlauth, letting an unauthenticated attacker bypass authentication and reach post-login code
    ("created session for anonymous"). The flaw is actively exploited (CISA KEV). The template distinguishes a
    vulnerable build from a patched one differentially: a probe whose RelayState decodes to the 20-byte
    "ctx=" + NUL marker reaches the unguarded path and returns HTTP 500 with the NetScaler internal error
    43524, while an equal-length control RelayState is rejected earlier and returns HTTP 200 "Malformed
    Assertion". A patched appliance returns the 200 "Malformed Assertion" for the probe too, so only the
    differing pair confirms the bypass.
  reference:
    - https://www.exploit.observer/?keyword=CVE-2026-19490&match=exact
    - https://subdomain.center/?engine=ammonites&keyword=netscaler&match=exact
  classification:
    cvss-metrics: 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
    cvss-score: 9.3
    cve-id: CVE-2026-19490
    cwe-id: CWE-288
  metadata:
    verified: false
    max-request: 2
  tags: cve,cve2026,netscaler,citrix,saml,auth-bypass,kev
http:
  - raw:
      - |
        POST /cgi/samlauth HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/x-www-form-urlencoded
        Accept: text/html

        SAMLResponse=AAAA&RelayState=Y3R4PQAAAAAAAAAAAAAAAAAAAAAAA%3D
      - |
        POST /cgi/samlauth HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/x-www-form-urlencoded
        Accept: text/html

        SAMLResponse=AAAA&RelayState=Y3R4PUFBQUFBQUFBQUFBQUFBQUE%3D

    req-condition: true
    matchers-condition: and
    matchers:
      - type: dsl
        dsl:
          - 'status_code_1 == 500'
          - 'contains(body_1, "43524")'
          - 'status_code_2 == 200'
          - 'contains(body_2, "Malformed Assertion")'
        condition: and

CVE-2026-19490.yaml on GitHub

References

Government sources

Other references

Other databases

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer, vedas-signatures. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.