CVE-2023-4966

Unauthenticated sensitive information disclosure

HIGH

7.5

CVSS Score

Published: October 10, 2023 at 01:12 PM UTC

Updated: July 31, 2026 at 04:30 AM UTC

2 products affected across 1 vendorNetScaler GatewayNetscaler Application Delivery Controller

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Severity

HIGH7.5

Exploitation

CISA KEV

Exploit prediction

EPSS 100%

SSVC

Active

Actively Exploited

CISA Known Exploited Vulnerabilities (KEV) Catalog

EPSS Score100.0%

EPSS (Exploit Prediction Scoring System) estimates a 100.0% chance this CVE is exploited in the wild within the next 30 days — higher than 100% of all CVEs. It complements CVSS: a high EPSS on a mid-severity CVE can still be urgent.

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.

Required Action

Apply mitigations and kill all active and persistent sessions per vendor instructions [https://www.netscaler.com/blog/news/cve-2023-4966-critical-security-update-now-available-for-netscaler-adc-and-netscaler-gateway/] OR discontinue use of the product if mitigations are unavailable.

Ransomware Use

Known

Added to KEV

Oct 18, 2023

Remediation Due

Nov 8, 2023

1086 days overdue

Notes

https://www.netscaler.com/blog/news/cve-2023-4966-critical-security-update-now-available-for-netscaler-adc-and-netscaler-gateway/, https://support.citrix.com/article/CTX579459/netscaler-adc-and-netscaler-gateway-security-bulletin-for-cve20234966-and-cve20234967

https://nvd.nist.gov/vuln/detail/CVE-2023-4966

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Netscaler Application Delivery Controller · Citrix

95%

12.1 ≤ v < 12.1-55.30012.1-FIPS ≤ v < 55.30012.1-NDcPP ≤ v < 55.30013.0 ≤ v < 13.0-92.1913.0 ≤ v < 92.1913.1 ≤ v < 13.1-37.16413.1 ≤ v < 13.1-49.1513.1 ≤ v < 49.1513.1-FIPS ≤ v < 37.16414.1 ≤ v < 14.1-8.5014.1 ≤ v < 8.5012.1-FIPS 12.1-NDcPP 13.0 13.1 13.1-FIPS 14.1

Affected range stops below 12.1-55.300, so it looks safe — our inference, not a vendor statement

Affected range stops below 13.0-92.19, so it looks safe — our inference, not a vendor statement

Affected range stops below 13.1-37.164, so it looks safe — our inference, not a vendor statement

Affected range stops below 13.1-49.15, so it looks safe — our inference, not a vendor statement

Affected range stops below 14.1-8.50, so it looks safe — our inference, not a vendor statement

Affected range stops below 37.164, so it looks safe — our inference, not a vendor statement

Affected range stops below 49.15, so it looks safe — our inference, not a vendor statement

Affected range stops below 55.300, so it looks safe — our inference, not a vendor statement

Affected range stops below 8.50, so it looks safe — our inference, not a vendor statement

Affected range stops below 92.19, so it looks safe — our inference, not a vendor statement

NetScaler Gateway · Citrix

95%

13.0 ≤ v < 13.0-92.1913.0 ≤ v < 92.1913.1 ≤ v < 13.1-49.1513.1 ≤ v < 49.1514.1 ≤ v < 14.1-8.5014.1 ≤ v < 8.5013.0 13.1 14.1

Affected range stops below 13.0-92.19, so it looks safe — our inference, not a vendor statement

Affected range stops below 13.1-49.15, so it looks safe — our inference, not a vendor statement

Affected range stops below 14.1-8.50, so it looks safe — our inference, not a vendor statement

Affected range stops below 49.15, so it looks safe — our inference, not a vendor statement

Affected range stops below 8.50, so it looks safe — our inference, not a vendor statement

Affected range stops below 92.19, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://support.citrix.com/article/CTX579459

References (3)

Third Party AdvisoryVDB Entry

Source: [email protected]

http://packetstormsecurity.com/files/175323/Citrix-Bleed-Session-Token-Leakage-Proof-Of-Concept.html

Vendor Advisory

Source: [email protected]

https://support.citrix.com/article/CTX579459

US Government Resource

Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-4966

SSVC — Action Prioritization

SSVCActiveAutomatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGH[email protected]

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: HIGH
Integrity: NONE
Availability: NONE

Vector?

Quick Info

StatusANALYZED

CWE

CWE-119NVD-CWE-noinfo

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