Citrix NetScaler ADC: Improper Input Validation (CVE-2023-3466)
Published Sources: CVE.org
- Actively exploited
- Source: CERT.at How we classify
What is affected, what to do
Reflected Cross-Site Scripting (XSS)
The vulnerability is being actively exploited; treat it as a priority. Update Citrix NetScaler ADC to version 49.13, Citrix NetScaler ADC to version 91.13, Citrix NetScaler ADC to version 37.159.
- Affected
- Citrix NetScaler ADC
lt 13.1..49.13 - Citrix NetScaler ADC
lt 13.0..91.13 - Citrix NetScaler ADC
lt 13.1-FIPS..37.159 - Citrix NetScaler ADC
lt 12.1-NDcPP..55.297 - Citrix NetScaler Gateway
lt 13.1..49.13 - Citrix NetScaler Gateway
lt 13.0..91.13
- Citrix NetScaler ADC
- Fixed in
- Citrix NetScaler ADC
49.13 - Citrix NetScaler ADC
91.13 - Citrix NetScaler ADC
37.159 - Citrix NetScaler ADC
55.297 - Citrix NetScaler Gateway
49.13 - Citrix NetScaler Gateway
91.13
- Citrix NetScaler ADC
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Metrics
8.3
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: Vendor (CNA), CVSS v3
8.3
CVSS v3
Severity High on the scale from 0 to 10.
Source: CVE.org
2.6 %
EPSS score
Moderate — model estimates 1-10% exploitation likelihood.
Source: FIRST EPSS, percentile 85.4
Show all metrics
- Severity
- High
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 102.96 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- actively exploitedSource: CERT.at How we classify
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 8.3 Methodology
CVSS v3
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 8.3
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 2.6 %
- Moderate — model estimates 1-10% exploitation likelihood.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 85.4
- Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
CWE
CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.
Read in glossary- CWE-20
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
Reflected Cross-Site Scripting (XSS)
Source: NVD (NIST), cvelistv5
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| Citrix | NetScaler ADC |
|
|
| Citrix | NetScaler Gateway |
|
|
| citrix | netscaler_application_delivery_controller |
|
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| citrix | netscaler_gateway |
|
|
Vendors and products
Weakness classes (CWE)
CWE-20Improper Input Validation
Class
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
Entry at MITRE CWE-20
References & sources
- support.citrix.comarticle/CTX561482/citrix-adc-and-citrix-gateway-security-bullet…Vendor advisory
- cert.atCERT.at: Update #1 - Sicherheitslücken, teils kritisch, in Citrix/Netscaler ADC und Gateway - aktiv ausgenützt - Updates verfügbarcert-at
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<a href="https://intel.neosec.eu/en/cve/CVE-2023-3466"><img src="https://intel.neosec.eu/badge/cve/CVE-2023-3466.svg?lang=en" alt="CVE-2023-3466 – NEOSEC Intel" height="20"></a>