CVE-2023-4967
published 2023-10-27CVE-2023-4967: Denial of Service in NetScaler ADC and NetScaler Gateway when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA Virtual Server
PriorityP180high7.5CVSS 3.1
AVNACLPRNUINSUCNINAH
ITWVulnCheck KEVRansomware
Exploited in the wild
EPSS
0.88%
54.5th percentile
Denial of Service in NetScaler ADC and NetScaler Gateway when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA Virtual Server
Affected
22 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| citrix | citrix_adc | — | — |
| citrix | citrix_gateway | — | — |
| citrix | netscaler_adc | — | — |
| citrix | netscaler_application_delivery_controller | 12.1 – 12.1-55.300 | — |
| citrix | netscaler_application_delivery_controller | >= 13.0 < 13.0-92.19 | 13.0-92.19 |
| citrix | netscaler_application_delivery_controller | >= 13.1 < 13.1-49.15 | 13.1-49.15 |
| citrix | netscaler_application_delivery_controller | 13.1 – 13.1-37.164 | — |
| citrix | netscaler_application_delivery_controller | >= 14.1 < 14.1-8.50 | 14.1-8.50 |
| citrix | netscaler_gateway | — | — |
| citrix | netscaler_gateway | >= 13.0 < 13.0-92.19 | 13.0-92.19 |
| citrix | netscaler_gateway | >= 13.1 < 13.1-49.15 | 13.1-49.15 |
| citrix | netscaler_gateway | >= 14.1 < 14.1-8.50 | 14.1-8.50 |
| citrix | xenserver | — | — |
| cloud_software_group | netscaler_adc | >= 12.1-FIPS < 55.300 | 55.300 |
| cloud_software_group | netscaler_adc | >= 12.1-NDcPP < 55.300 | 55.300 |
| cloud_software_group | netscaler_adc | >= 13.0 < 92.19 | 92.19 |
| cloud_software_group | netscaler_adc | >= 13.1 < 49.15 | 49.15 |
| cloud_software_group | netscaler_adc | >= 13.1-FIPS < 37.164 | 37.164 |
| cloud_software_group | netscaler_adc | >= 14.1 < 8.50 | 8.50 |
| cloud_software_group | netscaler_gateway | >= 13.0 < 92.19 | 92.19 |
| cloud_software_group | netscaler_gateway | >= 13.1 < 49.15 | 49.15 |
| cloud_software_group | netscaler_gateway | >= 14.1 < 8.50 | 8.50 |
Detection & IOCsextracted from sources · hover to see the quote
- →Monitor for active or persistent session tokens on NetScaler ADC/Gateway that survive patching; stolen tokens can bypass MFA and must be explicitly killed using Citrix CLI commands. ↗
- ·CVE-2023-4967 (DoS) only affects NetScaler ADC/Gateway when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server — devices not in these roles are not vulnerable. ↗
- ·NetScaler ADC/Gateway version 12.1 has reached end-of-life and will no longer receive patches; organizations on this version must upgrade to a supported release. ↗
- ·Patching alone is insufficient; active and persistent sessions must be explicitly terminated via CLI commands after patching, as stolen session tokens remain valid post-patch and can be used to bypass MFA. ↗
CVSS provenance
nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
vulncheck8.2HIGH
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GHSA
GHSA-wj66-97v8-j738: Denial of Service in NetScaler ADC and NetScaler Gateway when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA Virtual
ghsa_unreviewed·2023-10-27
CVE-2023-4967 [HIGH] CWE-119 GHSA-wj66-97v8-j738: Denial of Service in NetScaler ADC and NetScaler Gateway when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA Virtual
Denial of Service in NetScaler ADC and NetScaler Gateway when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA Virtual Server
VulnCheck
Citrix NetScaler ADC and NetScaler Gateway Improper Restriction of Operations within the Bounds of a Memory Buffer
vulncheck·2023·CVSS 8.2
CVE-2023-4967 [HIGH] Citrix NetScaler ADC and NetScaler Gateway Improper Restriction of Operations within the Bounds of a Memory Buffer
Citrix NetScaler ADC and NetScaler Gateway Improper Restriction of Operations within the Bounds of a Memory Buffer
Denial of Service in NetScaler ADC and NetScaler Gateway when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA Virtual Server
Affected: Citrix NetScaler ADC and NetScaler Gateway
Required Action: Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.
Known Ransomware Campaign Use: Known
Exploitation References: https://www.greynoise.io/blog/battling-ransomware-one-tag-at-a-time; https://hub.dragos.com/hubfs/312-Year-in-Review/2023/Dragos-2023-Year-in-Review-Full-Report.pdf; https://www.ptsecurity.com/ru-ru/research/analytics/itogi-proektov-po-rassledovaniyu-i
Citrix
NetScaler ADC and NetScaler Gateway Security Bulletin for CVE-2023-4966 and CVE-2023-4967
vendor_citrix·2023-10-17·CVSS 7.5
CVE-2023-4966 [HIGH] CWE-119 NetScaler ADC and NetScaler Gateway Security Bulletin for CVE-2023-4966 and CVE-2023-4967
NetScaler ADC and NetScaler Gateway Security Bulletin for CVE-2023-4966 and CVE-2023-4967
Pre-requisites CWE CVE-2023-4966 Sensitive information disclosure Application must be configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server CWE-119 CVE-2023-4967 Denial of service Appliance must be configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server CWE-119
CVE References: CVE-2023-4966, CVE-2023-4967
Affected Products: Citrix ADC, Citrix Gateway, NetScaler ADC, NetScaler Gateway, XenServer
Severity: Critical
No detection rules found.
No public exploits indexed.
Tenable
CVE-2023-4966 (CitrixBleed): Invalidate Active or Persistent Sessions To Prevent Further Compromise
blogs_tenable·2023-12-06·CVSS 9.4
[CRITICAL] CVE-2023-4966 (CitrixBleed): Invalidate Active or Persistent Sessions To Prevent Further Compromise
## Cloud Exposure
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## Vulnerability Exposure
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## AI Exposure
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## OT/IoT Exposure
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## Identity Exposure
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## Business needs
Active Directory
AI Security Posture Management (AI-SPM)
AWS security
Azure security
Cloud Security Posture Man
Tenable
Frequently Asked Questions for CitrixBleed (CVE-2023-4966)
blogs_tenable·2023-11-20·CVSS 9.4
[CRITICAL] Frequently Asked Questions for CitrixBleed (CVE-2023-4966)
## Cloud Exposure
Tenable Cloud Security (CNAPP) Request a demo
Tenable Cloud Vulnerability Management Request a demo
Tenable CIEM Request a demo
Secure your cloud
## Vulnerability Exposure
Tenable Vulnerability Management Try for free
Tenable Security Center Request a demo
Tenable Web App Scanning Try for free
Tenable Patch Management Request a demo
Tenable Enclave Security Request a demo
Tenable Attack Surface Management Request a demo
Tenable Nessus Try for free
## AI Exposure
Tenable AI Exposure Request a demo
## OT/IoT Exposure
Tenable OT Security Request a demo
## Identity Exposure
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## Business needs
Active Directory
AI Security Posture Management (AI-SPM)
AWS security
Azure security
Cloud Security Posture Man
Wiz
Crying Out Cloud - November Newsletter | Wiz
blogs_wiz·2023-11-01·CVSS 9.8
CVE-2023-42115 [CRITICAL] Crying Out Cloud - November Newsletter | Wiz
The past month has brought a series of vulnerabilities and security incidents that have left users affected. Amidst the noise, we've taken it upon ourselves to curate the most significant developments for you.
Here are our top picks of cloud security highlights!
## 🐞 High Profile Vulnerabilities
## Critical and high severity 0day vulnerabilities in Exim
Multiple vulnerabilities were disclosed in Exim Mail Transfer Agent (MTA), including CVE-2023-42115, which is a critical vulnerability enabling unauthenticated attackers to remotely execute code on publicly exposed Exim servers with a specific non-default configuration. This issue results from improper input validation that leads to writing arbitrary code past the end of the buffer.
According to Wiz data, although Exim is very prevalen
Unit42
Threat Brief: Citrix Bleed CVE-2023-4966
blogs_unit42·2023-11-01·CVSS 9.4
CVE-2023-4966 [CRITICAL] Threat Brief: Citrix Bleed CVE-2023-4966
## Executive Summary
Unit 42 stopped monitoring this threat and updating the brief on Aug. 14, 2025. Please refer to the Citrix website for the latest information.
On Oct. 10, 2023, Citrix published a patch for their Netscaler ADC and Netscaler Gateway products. One particular vulnerability that this patch is meant to mitigate has come to be known as Citrix Bleed (CVE-2023-4966).
This nickname was given because the vulnerability can leak sensitive information from the device’s memory, which can include session tokens. Attackers can then use these credentials to gain a foothold into systems via session hijacking. At the time of the patch, Citrix was unaware of ongoing attacks using this vulnerability but has since stated that they have observed threat actors using it.
The Unit 42 Incide
Unit42
Threat Brief: Citrix Bleed CVE-2023-4966
blogs_unit42·2023-11-01·CVSS 9.4
CVE-2023-4966 [CRITICAL] Threat Brief: Citrix Bleed CVE-2023-4966
Threat Research Center
High Profile Threats
Vulnerabilities
## Threat Brief: Citrix Bleed CVE-2023-4966
Unit 42
Published: November 1, 2023
High Profile Threats
Vulnerabilities
Citrix
Citrix Netscaler
CVE-2023-4966
## Executive Summary
Unit 42 stopped monitoring this threat and updating the brief on Aug. 14, 2025. Please refer to the Citrix website for the latest information.
On Oct. 10, 2023, Citrix published a patch for their Netscaler ADC and Netscaler Gateway products. One particular vulnerability that this patch is meant to mitigate has come to be known as Citrix Bleed ( CVE-2023-4966 ).
This nickname was given because the vulnerability can leak sensitive information from the device’s memory, which can include session tokens. Attackers can then use these credentials
Tenable
CVE-2023-4966: Citrix NetScaler ADC and NetScaler Gateway Information Disclosure Exploited in the Wild
blogs_tenable·2023-10-18·CVSS 9.4
[CRITICAL] CVE-2023-4966: Citrix NetScaler ADC and NetScaler Gateway Information Disclosure Exploited in the Wild
## Cloud Exposure
Tenable Cloud Security (CNAPP) Request a demo
Tenable Cloud Vulnerability Management Request a demo
Tenable CIEM Request a demo
Secure your cloud
## Vulnerability Exposure
Tenable Vulnerability Management Try for free
Tenable Security Center Request a demo
Tenable Web App Scanning Try for free
Tenable Patch Management Request a demo
Tenable Enclave Security Request a demo
Tenable Attack Surface Management Request a demo
Tenable Nessus Try for free
## AI Exposure
Tenable AI Exposure Request a demo
## OT/IoT Exposure
Tenable OT Security Request a demo
## Identity Exposure
Tenable Identity Exposure Request a demo
## Business needs
Active Directory
AI Security Posture Management (AI-SPM)
AWS security
Azure security
Cloud Security Posture Man
Bleepingcomputer
New critical Citrix NetScaler flaw exposes 'sensitive' data
blogs_bleepingcomputer·2023-10-10·CVSS 9.4
CVE-2023-4966 [CRITICAL] New critical Citrix NetScaler flaw exposes 'sensitive' data
## New critical Citrix NetScaler flaw exposes 'sensitive' data
## Bill Toulas
Citrix NetScaler ADC and NetScaler Gateway are impacted by a critical severity flaw that allows the disclosure of sensitive information from vulnerable appliances.
The flaw is tracked as CVE-2023-4966 and has received a CVSS rating of 9.4, being remotely exploitable without requiring high privileges, user interaction, or high complexity.
However, there's the prerequisite of the appliance to be configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or an AAA virtual server for it to be vulnerable to attacks.
While the flaw's exploitation can lead to "sensitive information disclosure," the vendor has not provided any details about what information is exposed.
A second vulnerability disclosed
Greynoiseio
CVE-2023-4966 Helps Usher In A Baker’s Dozen Of Citrix Tags To Further Help Organizations Mitigate Harm
blogs_greynoiseio·CVSS 9.4
[CRITICAL] CVE-2023-4966 Helps Usher In A Baker’s Dozen Of Citrix Tags To Further Help Organizations Mitigate Harm
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Why GreyNoise
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2023-10-27
Published
Exploited in the wild