Vulnerability report

Active exploitation observed Confirmed confidence In CISA KEV

CVE-2026-19490

NetScaler ADC and NetScaler Gateway Security Bulletin for CVE-2026-19490

NetScaler / ADC · 14.1 to <= 73.32

Watch CVE-2026-19490 Browse KEV feed
Severity
CVSS 9.3 · Critical
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
23.2%
First observed
03 Sep 2026
Last observed
05 Oct 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-19490 is an unauthenticated NetScaler ADC and NetScaler Gateway Security Bulletin for CVE-2026-19490. Vulnerability in NetScaler ADC and NetScaler Gateway. This issue affects ADC: from 14.1 through 73.32 and...

Is it exploited?

Yes. Previdian sensors observed exploitation attempts with confirmed confidence. Listed in CISA KEV. Also confirmed by third-party sources.

Who is affected?

NetScaler / ADC 14.1 to <= 73.32.

What should we do?

Patch immediately, validate internet-facing exposure, and monitor for matching requests.

Overview

Vulnerability in NetScaler ADC and NetScaler Gateway

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.

NetScaler Affected
ADC
Through 73.32 Through 63.21
NetScaler Affected
Gateway
Through 73.32 Through 63.21
Published
19 Aug 2026
Exploitation Reported
03 Sep 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

cisa

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

Previdian

Recorded 03 Sep 2026

Previdian independently recorded this as exploited after first seeing it in honeypot sensors.

Active exploitation observed

Previdian sensor

First observed 03 Sep 2026

Previdian first observed exploitation attempts targeting this vulnerability in our honeypot sensors.

Proof of concept available

GitHub

Recorded 02 Sep 2026

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
Previdian Sensors First 2026-09-03 11:43 UTC
CISA 2026-09-09 19:20 UTC
CVE 2026-09-09 20:01 UTC
The Hacker News 2026-09-27 08:21 UTC
Tenable Blog 2026-09-27 10:21 UTC

Operational indicators for this CVE are listed under Detection.

Sensor telemetry

First-party evidence of exploitation activity

Previdian sensors recorded exploitation attempts targeting this vulnerability. The cards and chart show volume, unique attackers, and daily activity.

68

Attempts observed

16

Unique attacker IPs

8

Attacker countries

AU · BR · DE · HK · JP · RO · TW · US

3

Sensors observed

CVE-2026-19490 exploitation attempts over the last 48 days

Daily events observed by Previdian sensors

Updated 19 Oct 2026

0
6
4
0
0
8
36
2
0
0
0
0
0
0
0
0
0
0
0
0
6
0
0
0
0
0
0
0
0
0
0
3
0
3
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2 Sep 12 Sep 22 Sep 2 Oct 19 Oct

First observed 03 Sep 2026 · Last observed 05 Oct 2026

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Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
10
5
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Attacker IP Indicators

Attacker IP indicators observed · available in Pro and Enterprise.

Sensor-derived attacker IP indicators are available to Pro and Enterprise accounts under Detection and through the Pro API.

Learn about Pro API access

Risk and context

Severity, weaknesses, and research context

CVSS v4.0

9.3 Critical

Potential damage if exploited. Separate from whether attackers are using it.

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

EPSS

23.2%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Authentication Bypass Using an Alternate Path or Channel CWE-288

Recent mention · Security Affairs

Citrix Confirmed Two New NetScaler Flaws Exploited as Zero-Day

Citrix confirmed two critical NetScaler zero-days were exploited before patches were available, with attackers able to remotely execute code. Citrix confirmed that two critical zero-day vulnerabilities in NetScaler ADC and NetScaler Gateway were exploited before the company...

Read full advisory

All CVSS Scores

CVSS v4.0 9.3 Critical

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 v3.1 9.8 Critical

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

All Mentions

Recent mention · Security Affairs

Citrix Confirmed Two New NetScaler Flaws Exploited as Zero-Day

Security Affairs · 27 Sep 2026

Citrix confirmed two critical NetScaler zero-days were exploited before patches were available, with attackers able to remotely execute code. Citrix confirmed that two critical zero-day vulnerabilities in NetScaler ADC and NetScaler Gateway were exploited before the company released patches. The flaws allow remote code execution, meaning attackers can potentially take control of affected appliances. The […]

Recent mention · Tenable Blog

Frequently asked questions about reported Citrix NetScaler zero-day vulnerabilities

Tenable Blog · 27 Sep 2026

There are reportedly two unpatched zero-day Citrix NetScaler vulnerabilities capable of enabling remote code execution that have been actively exploited in the wild, with no patches available at this time.Key takeawaysReports indicate that there are two critical zero-day vulnerabilities in Citrix NetScaler.The reports originate from a pre-notification sent out ahead of public disclosure, so there are currently no specific details about these flaws and no patches available.This post will be updated as new information becomes available.BackgroundTenable's Research Special Operations (RSO)...

Recent mention · The Hacker News

Warning: Two Unpatched Citrix NetScaler RCE Zero-Days Under Active Exploitation

The Hacker News · 27 Sep 2026

Two new unpatched zero-day vulnerabilities in Citrix NetScaler ADC and NetScaler Gateway appliances that allow remote code execution are being actively exploited in the wild, security firm watchTowr said on September 26. Citrix has not confirmed the flaws or published a fix. Some administrators say they have taken appliances offline rather than wait for one to be available. NetScaler ADC and

Recent mention · NCSC Security Advisories

NCSC-2026-0318 [1.01] [H/H] Kwetsbaarheden verholpen in Citrix NetScaler ADC en NetScaler Gateway

NCSC Security Advisories · 07 Sep 2026

Citrix heeft kwetsbaarheden verholpen in NetScaler ADC en NetScaler Gateway. De kwetsbaarheid met kenmerk CVE-2026-19489 betreft een memory overflow in NetScaler ADC en NetScaler Gateway, wanneer de producten zijn geconfigureerd als SIP ALG binnen een Large Scale NAT (LSN) groep. Deze fout in de geheugenallocatie kan leiden tot onvoorspelbaar gedrag of een denial of service, waardoor de normale werking van het systeem verstoord kan worden. De kwetsbaarheid met kenmerk CVE-2026-19490 maakt het voor een aanvaller mogelijk om via een alternatieve route de normale authenticatiemechanismen te...

Recent mention · BleepingComputer

Critical Citrix NetScaler auth bypass now leveraged in attacks

BleepingComputer · 04 Sep 2026

Attackers have begun targeting a critical-severity Citrix NetScaler auth bypass flaw (CVE-2026-19490) in the wild, according to vulnerability intelligence company Previdian. [...]

Recent mention · CERT Polska

Podatności w NetScaler ADC i NetScaler Gateway

CERT Polska · 21 Aug 2026

Zespół CERT Polska informuje o podatnościach znalezionych w produktach NetScaler ADC (dawniej Citrix ADC) oraz NetScaler Gateway (dawniej Citrix Gateway).Producent opublikował biuletyn bezpieczeństwa opisujący dwie podatności: CVE-2026-19489 oraz CVE-2026-19490.Szczególnie istotna jest luka CVE-2026-19490, która umożliwia obejście mechanizmów uwierzytelniania na urządzeniach skonfigurowanych jako Gateway (SSL VPN, ICA Proxy, CVPN, RDP Proxy) lub AAA vserver. W wybranych wersjach jej wykorzystanie wymaga dodatkowej konfiguracji SAML.Druga podatność (CVE-2026-19489) dotyczy możliwości...

Recent mention · Rapid7

CVE-2026-19490: Critical Vulnerability Affecting Citrix NetScaler ADC and NetScaler Gateway

Rapid7 · 19 Aug 2026

OverviewOn August 19, 2026, a security advisory was published for CVE-2026-19490, a critical authentication bypass vulnerability affecting Citrix NetScaler ADC and NetScaler Gateway. The vulnerability carries a CVSS v4.0 base score of 9.3 and can be exploited remotely by an unauthenticated attacker over the network without user interaction or elevated privileges.NetScaler ADC and NetScaler Gateway are widely deployed enterprise networking products commonly positioned at or near the network perimeter. NetScaler ADC provides application delivery, traffic management, load balancing, SSL/TLS...

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

TarPeg007/CVE-2026-19490

github · Created 2026-09-02 15:43:53 UTC · 0 stars · AI assessment 90%

NetScaler ADC/Gateway SAML unsigned-assertion bypass via HTTP-Redirect binding (CTX696939) - root cause analysis + PoC

Timeline

From disclosure to observed exploitation

  1. 10:21 UTC

    KEV confirmed by Tenable Blog

    Exploitation attested by an external source

  2. 08:21 UTC

    KEV confirmed by The Hacker News

    Exploitation attested by an external source

  3. 20:01 UTC

    KEV confirmed by CVE

    Exploitation attested by an external source

  4. 19:20 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  5. 11:28 UTC

    Indicators of compromise added (16)

    Indicators of compromise recorded

  6. 11:28 UTC

    Observed by Previdian sensors

    Evidence-backed exploitation signal

  7. 15:43 UTC

    Public PoC available

    Public proof-of-concept code published

  8. 14:20 UTC

    Added to the Previdian watchlist

    Pro and Enterprise Watch users had 2 weeks of early warning before CISA KEV. Also 2 weeks before Previdian confirmed it as a KEV.

  9. 12:54 UTC

    CVE published

    Vulnerability disclosed publicly

  10. 17:39 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2026-19490

Sample API response 
{
  "cve_id": "CVE-2026-19490",
  "confidence": "Confirmed",
  "cvss_score": 9.3,
  "cvss_estimated": false,
  "epss_score": 0.23158,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 68, "sensors": 3 }
}