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CVE-2023-4966

Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow

9.4 CRITICALActively exploited (CISA KEV)Used in ransomwareEPSS 100.0%
  1. Published10 Oct 2023
  2. Added to CISA KEV18 Oct 2023
  3. Remediation due8 Nov 2023
Actively exploited (CISA KEV)

Citrix NetScaler ADC and NetScaler Gateway contain a buffer overflow vulnerability that allows for sensitive information disclosure when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server.

Added to KEV: 18 Oct 2023Federal remediation due: 8 Nov 2023Used in ransomware

Description

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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityLow
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L

Affected products

Citrix NetScaler Application Delivery Controller≥ 13.0 < 13.0-92.19 · ≥ 13.1 < 13.1-49.15 · ≥ 14.1 < 14.1-8.50 · ≥ 12.1 < 12.1-55.300
Citrix NetScaler Gateway≥ 13.0 < 13.0-92.19 · ≥ 13.1 < 13.1-49.15 · ≥ 14.1 < 14.1-8.50

Remediation

Fixed in
Citrix NetScaler Application Delivery Controller≥ 13.0-92.19
Citrix NetScaler Gateway≥ 13.0-92.19

References

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Frequently asked

Is CVE-2023-4966 being actively exploited?

Yes. CVE-2023-4966 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 18 Oct 2023. It has been used in ransomware campaigns.

How severe is CVE-2023-4966?

CVE-2023-4966 has a CVSS 3.1 base score of 9.4, rated critical. EPSS estimates a 100.0% probability of exploitation.

Which products are affected by CVE-2023-4966?

Affected products include Citrix NetScaler Application Delivery Controller, Citrix NetScaler Gateway.

How do I fix CVE-2023-4966?

Upgrade affected software to a fixed version, for example Citrix NetScaler Application Delivery Controller 13.0-92.19, Citrix NetScaler Gateway 13.0-92.19 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2023-4966 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, a risk for it never ranks below high, and the update that fixes it moves to the Emergency patch lane. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.