NetScaler: CitrixBleed 2 memory overread (CVE-2025-5777) (CVE-2025-5777) #shorts

Summary

Welcome to CyberTalk. Today we cover CVE-2025-5777, known as CitrixBleed 2, a critical memory-disclosure flaw in Citrix NetScaler ADC and Gateway. This vulnerability is already being exploited in the wild, and Citrix has released patches—so immediate action is required.

Product details

Affected products are Citrix NetScaler ADC and Citrix NetScaler Gateway running versions prior to 14.1-43.56 and 13.1-58.32. These include configurations as VPN virtual servers, ICA Proxy, CVPN, RDP Proxy, AAA virtual servers, and the NetScaler Management Interface.

Vulnerability type summary

This issue is classified under CWE-125: Out-of-bounds Read. An attacker can craft malicious requests that bypass input validation and read memory beyond allocated buffers.

Details of the vulnerability

When NetScaler is configured as a Gateway or AAA virtual server—or when handling management interface traffic—insufficient input validation allows overread of memory. Attackers can extract sensitive information from process memory, including credentials and session tokens. Public reports indicate thousands of unpatched systems are exposed. The flaw has seen real-world exploitation under the label CitrixBleed 2, with automated scanners and Metasploit modules available.

Conclusion

CVE-2025-5777 poses a serious data-leak risk for any organization using vulnerable NetScaler instances. To mitigate, upgrade immediately to version 14.1-43.56 or 13.1-58.32 (or later). Review logs for abnormal Gateway or AAA activity, and isolate unpatched appliances. Stay safe and keep your infrastructure current.

Watch the full video on YouTube: CVE-2025-5777

Remediation and exploitation details

This chain involves the following actors

  • Attacker: Exploits CitrixBleed 2 to read server memory
  • Administrator: Deploys patches and monitors system health

This following systems are involved

  • Citrix NetScaler ADC (Application delivery controller): Processes incoming client requests and applies gateway functions
  • Citrix NetScaler Gateway (Secure remote access gateway): Front-ends remote desktop, application and virtual private network access

Attack entry point

  • VPN virtual server: Handles remote private network tunnels
  • ICA Proxy virtual server: Proxies Citrix application sessions
  • CVPN virtual server: Manages client VPN connections
  • RDP Proxy virtual server: Proxies remote desktop sessions
  • AAA virtual server: Performs authentication, authorization, and audit
  • Management Interface: Web interface for configuration and monitoring

Remediation actions

Administrator
Upgrade Citrix NetScaler ADC and Gateway to versions 14.1-43.56 or later, or 13.1-58.32 or later
All affected NetScaler instances
Administrator
Review firewall and access-control rules to limit management interface exposure
Network perimeter
Administrator
Monitor server logs for repeated malformed requests and unusual memory-read errors
NetScaler ADC/Gateway logging subsystem

Exploitation actions

Insufficient input validation

Attacker
Crafts a specially malformed HTTP request targeting the VPN or AAA endpoint
Citrix NetScaler ADC or Gateway
Examples:
  • Send an HTTP POST with oversized parameter values in the session initiation payload
  • Include control sequences that bypass length checks

Buffer overread

Attacker
Submits the malicious request to trigger an out-of-bounds memory read
Gateway virtual server or AAA virtual server
Examples:
  • Use a command-line tool to repeatedly send the crafted request until memory regions expose sensitive data
  • Automate payload delivery with a custom script to cycle through memory offsets

Memory disclosure

Attacker
Receives leaked memory fragments in server responses
NetScaler ADC/Gateway
Examples:
  • Observe session tokens, encryption keys or user passwords in the HTTP response body
  • Parse returned binary data to extract clear-text credentials

Credential reuse and lateral movement

Attacker
Aggregates recovered data and uses it for further intrusion
Target network
Examples:
  • Log in with stolen credentials to internal applications
  • Pivot from gateway to backend servers for data exfiltration

Related Content

NOTE: The following related content has not been vetted and may be unsafe.

CVE database technical details

CVE ID
CVE-2025-5777
Description
Insufficient input validation leading to memory overread when the NetScaler is configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server
Provider
Citrix
CWE / problem types
CWE-125 Out-of-bounds Read
Affected Software Versions
NetScaler:ADC:[{'lessThan': '43.56', 'status': 'affected', 'version': '14.1', 'versionType': 'patch'}, {'lessThan': '58.32', 'status': 'affected', 'version': '13.1', 'versionType': 'patch'}],NetScaler:Gateway:[{'lessThan': '43.56', 'status': 'affected', 'version': '14.1', 'versionType': 'patch'}, {'lessThan': '58.32', 'status': 'affected', 'version': '13.1', 'versionType': 'patch'}]
Date Published
2025-06-17T12:29:34.506Z
Last Updated
2025-06-26T03:55:14.617Z