Saturday, June 15, 2024

Citrix Bleed: PoC Released for Citrix NetScaler Zero-Day Vulnerability

Two vulnerabilities were disclosed by Citrix, which were CVE-2023-4966 and CVE-2023-4967, with critical and high severities, respectively. Of these two, CVE-2023-4966 has been released with a publicly available PoC. This vulnerability is associated with a sensitive information disclosure score of 9.4 (Critical).

This vulnerability existed in the Citrix Netscaler ADC and Netscaler Gateway versions before their latest release. However, Citrix has fixed this vulnerability, and patches have been issued.

CVE-2023-4966 – Proof of Concept

For diving deep, the vulnerable devices were looked upon inside the /netscaler/nsppe, the Netscaler packet processing engine containing the complete TCP/IP network stack and multiple HTTP services.

Additionally, the Ghidra tool was used to decompile the nsppe, and BinExport to create a BinDiff file. Comparing the compiled BinDiff file of two vulnerable devices, there were more than 50 different functions.

Two functions, ns_aaa_oauth_send_openid_config and ns_aaa_oauthrp_send_openid_config, were found to perform the same function to implement the OpenID Connect Discovery endpoint. Both of these functions are accessible without authentication.


The vulnerability existed on the return value of snprintf, which determines the number of bytes to send for the ns_vpn_send_response. As part of exploitation, snprintf is supplied with an exceeded buffer size of 0x20000 bytes.

Furthermore, a complete Proof of Concept report has been published by AssetNote, providing detailed information on the exploitation methods, detailed steps, and others.

Affected Products

CVE IDAffected ProductsFixed in Version
CVE-2023-4966NetScaler ADC and NetScaler Gateway 14.1 before 14.1-8.50NetScaler ADC and NetScaler Gateway 14.1-8.50 and later releases
NetScaler ADC and NetScaler Gateway 13.1 before 13.1-49.15NetScaler ADC and NetScaler Gateway 13.1-49.15 and later releases of 13.1
NetScaler ADC and NetScaler Gateway 13.0 before 13.0-92.19NetScaler ADC and NetScaler Gateway 13.0-92.19 and later releases of 13.0
NetScaler ADC 13.1-FIPS before 13.1-37.164NetScaler ADC 13.1-FIPS 13.1-37.164 and later releases of 13.1-FIPS
NetScaler ADC 12.1-FIPS before 12.1-55.300NetScaler ADC 12.1-FIPS 12.1-55.300 and later releases of 12.1-FIPS
NetScaler ADC 12.1-NDcPP before 12.1-55.300NetScaler ADC 12.1-NDcPP 12.1-55.300 and later releases of 12.1-NDcPP

Users of these products are recommended to upgrade to the latest versions of these products to prevent these vulnerabilities from getting exploited.

Protect yourself from vulnerabilities using Patch Manager Plus to patch over 850 third-party applications quickly. Try a free trial to ensure 100% security.


Latest articles

Sleepy Pickle Exploit Let Attackers Exploit ML Models And Attack End-Users

Hackers are targeting, attacking, and exploiting ML models. They want to hack into these...

SolarWinds Serv-U Vulnerability Let Attackers Access sensitive files

SolarWinds released a security advisory for addressing a Directory Traversal vulnerability which allows a...

Smishing Triad Hackers Attacking Online Banking, E-Commerce AND Payment Systems Customers

Hackers often attack online banking platforms, e-commerce portals, and payment systems for illicit purposes.Resecurity...

Threat Actor Claiming Leak Of 5 Million Ecuador’s Citizen Database

A threat actor has claimed responsibility for leaking the personal data of 5 million...

Ascension Hack Caused By an Employee Who Downloaded a Malicious File

Ascension, a leading healthcare provider, has made significant strides in its investigation and recovery...

AWS Announced Malware Detection Tool For S3 Buckets

Amazon Web Services (AWS) has announced the general availability of Amazon GuardDuty Malware Protection...

Hackers Exploiting MS Office Editor Vulnerability to Deploy Keylogger

Researchers have identified a sophisticated cyberattack orchestrated by the notorious Kimsuky threat group.The...
Eswar is a Cyber security content editor with a passion for creating captivating and informative content. With years of experience under his belt in Cyber Security, he is covering Cyber Security News, technology and other news.

Free Webinar

API Vulnerability Scanning

71% of the internet traffic comes from APIs so APIs have become soft targets for hackers.Securing APIs is a simple workflow provided you find API specific vulnerabilities and protect them.In the upcoming webinar, join Vivek Gopalan, VP of Products at Indusface as he takes you through the fundamentals of API vulnerability scanning..
Key takeaways include:

  • Scan API endpoints for OWASP API Top 10 vulnerabilities
  • Perform API penetration testing for business logic vulnerabilities
  • Prioritize the most critical vulnerabilities with AcuRisQ
  • Workflow automation for this entire process

Related Articles