Netscaler Application Delivery ControllerApplication · Citrix

CVE-2023-4966

HIGH · 7.5 CVSS v3.1 Published 2023-10-10

Fix available

A fix is available. Upgrade to 12.1-55.300 / 13.0-92.19 or later.

See remediation →

100/100

Remediation priority · Urgent

In the wild Ransomware High EPSS Public exploit Remotely reachable No privileges Zero-click

Official description

NVD · unedited

Sensitive information disclosure in NetScaler ADC and NetScaler Gateway when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA  virtual server.

Technical summary

dbcve analysis · moderate confidence

Sensitive information disclosure vulnerability in Citrix NetScaler ADC and NetScaler Gateway when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server. The vulnerability allows unauthorized disclosure of sensitive information.

MitigationApply the vendor-provided patches for NetScaler ADC and NetScaler Gateway. If immediate patching is not possible, consider disabling affected virtual server configurations or implementing additional access controls.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions

NVD · CPE data

Netscaler Application Delivery ControllerApplication

Affected:>= 12.1, < 12.1-55.300>= 13.0, < 13.0-92.19>= 13.1, < 13.1-37.164>= 13.1, < 13.1-49.15>= 14.1, < 14.1-8.50

Netscaler GatewayApplication

Affected:>= 13.0, < 13.0-92.19>= 13.1, < 13.1-49.15>= 14.1, < 14.1-8.50

CVSS breakdown

From the vector

Attack vector: Network
Complexity: Low
Privileges: None
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

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

Am I affected?

dbcve checks

Work through these to decide whether this CVE applies to you.

Identify NetScaler product type and version

Run 'show version' in the NetScaler CLI or check the web interface under System > Information > Version. Record the exact build number (for example, 13.0-91.12 or 14.1-8.42).

Affected if The installed version falls within any of these ranges: 12.1 before 55.300, 13.0 before 92.19, 13.1 before 37.164 or before 49.15, or 14.1 before 8.50.
Confirm NetScaler ADC is in use

Run 'show hardware' or check the web interface System > Diagnostics > Show Hardware. Look for 'NetScaler ADC' in the product description.

Affected if The device is running NetScaler ADC and the version is vulnerable per step 1.
Confirm NetScaler Gateway is in use

Run 'show hardware' or check the web interface System > Diagnostics > Show Hardware. Look for 'NetScaler Gateway' in the product description.

Affected if The device is running NetScaler Gateway and the version is vulnerable per step 1.
Check for configured Gateway virtual servers

Run 'show vpn vserver' in the CLI or navigate to NetScaler Gateway > Virtual Servers in the web interface. Look for virtual servers with type VPN, ICA Proxy, CVPN, or RDP Proxy that are in UP state.

Affected if Any Gateway virtual server (VPN, ICA Proxy, CVPN, or RDP Proxy) is configured and enabled.
Check for configured AAA virtual servers

Run 'show aaa vserver' in the CLI or navigate to Security > AAA > Virtual Servers in the web interface. Look for AAA virtual servers that are in UP state.

Affected if Any AAA virtual server is configured and enabled.

The environment is affected if running a vulnerable NetScaler ADC or Gateway version AND at least one Gateway virtual server (VPN, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server is configured and enabled.

Generated from the published advisory. Verify against your own configuration.

Remediation

dbcve · scoped

Upgrade available Upgrade to 12.1-55.300 / 13.0-92.19 / 13.1-37.164 or later

Fixed in 12.1-55.30013.0-92.1913.1-37.164

Interim mitigation

Apply the vendor-provided patches for NetScaler ADC and NetScaler Gateway. If immediate patching is not possible, consider disabling affected virtual server configurations or implementing additional access controls.

Recommended fix High confidence

Upgrade to the minimum fixed build for your version: ADC 12.1 to 12.1-55.300+, ADC 13.0 to 13.0-92.19+, ADC 13.1 to 13.1-49.15+, Gateway 13.0 to 13.0-92.19+, Gateway 13.1 to 13.1-49.15+, Gateway 14.1 to 14.1-8.50+

1. Identify the current NetScaler ADC and/or NetScaler Gateway version by navigating to the NetScaler UI or running 'show version' via CLI
2. Determine which deployment type is in use: Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server, as only these configurations are vulnerable
3. For NetScaler ADC 12.1: Upgrade to version 12.1-55.300 or later
4. For NetScaler ADC 13.0: Upgrade to version 13.0-92.19 or later
5. For NetScaler ADC 13.1: Upgrade to version 13.1-49.15 or later (or 13.1-37.164 if on the 13.1-37 branch)
6. For NetScaler Gateway 13.0: Upgrade to version 13.0-92.19 or later
7. For NetScaler Gateway 13.1: Upgrade to version 13.1-49.15 or later
8. For NetScaler Gateway 14.1: Upgrade to version 14.1-8.50 or later

Caveat Review Citrix release notes before upgrading; some builds may introduce configuration or compatibility changes; test in non-production environment first

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Netscaler Application Delivery Controller Exploited in the wild — priority engagement

Consultation4.0 h
Implementation8.0 h
Testing6.0 h
Review / QA2.0 h

20.0 hours of engineering $3,500

Get it fixed fast

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Scan for this in your stack

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References

Primary sources

packetstormsecurity.comProof of Concept
support.citrix.comVendor Advisory
packetstormsecurity.comThird Party AdvisoryVDB Entry
www.cisa.govUS Government Resource
nvd.nist.govNVD record

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-4966 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2023-4966?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here

Verified mitigations, workarounds, and config changes
Version or environment caveats, and links to real fixes
No weaponised exploit code, or anything meant to cause harm
No spam, self-promotion, credentials, or personal data

At a glance

Exploited in the wildOn CISA’s known-exploited list · agencies must fix by 2023-11-08

A fix existsUpgrade to 12.1-55.300 / 13.0-92.19 or later

Severity 7.5 High

Exploit likelihood EPSS, next 30 days 100.0%

Affects: Netscaler Application Delivery Controller

Remediation

Being exploited — close it fast

Fix this in Netscaler Application Delivery Controller 20 hrs · Moderate

Typical engagement from $3,500

Get it fixed fast See the full breakdown ↓

This CVE is on CISA’s actively-exploited list, so the clock is real — a vetted specialist can deliver a reviewed fix for your staging environment quickly.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

Check your environment

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

Affected products & versions

CVSS breakdown

Am I affected?

Remediation

References