CVE-2025-5777
📋 TL;DR
CVE-2025-5777 (CitrixBleed 2) is a memory disclosure vulnerability in Citrix NetScaler ADC and Gateway appliances. Insufficient input validation allows attackers to read sensitive memory contents when devices are configured as VPN/AAA servers. This affects organizations using Citrix NetScaler for remote access.
💻 Affected Systems
- Citrix NetScaler ADC
- Citrix NetScaler Gateway
📦 What is this software?
Netscaler Application Delivery Controller by Citrix
View all CVEs affecting Netscaler Application Delivery Controller →
Netscaler Application Delivery Controller by Citrix
View all CVEs affecting Netscaler Application Delivery Controller →
Netscaler Application Delivery Controller by Citrix
View all CVEs affecting Netscaler Application Delivery Controller →
Netscaler Application Delivery Controller by Citrix
View all CVEs affecting Netscaler Application Delivery Controller →
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise via memory disclosure leading to credential theft, session hijacking, and lateral movement across the network.
Likely Case
Session token and credential theft enabling unauthorized access to internal resources and potential data exfiltration.
If Mitigated
Limited impact with proper network segmentation, monitoring, and immediate patching.
🎯 Exploit Status
Actively exploited in the wild with public proof-of-concept code available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 14.1-31.46, 13.1-57.46, 13.0-102.46, 12.1-71.46
Vendor Advisory: https://support.citrix.com/support-home/kbsearch/article?articleNumber=CTX693420
Restart Required: Yes
Instructions:
1. Download appropriate firmware from Citrix support. 2. Backup configuration. 3. Apply firmware update. 4. Reboot appliance. 5. Verify patch installation.
🔧 Temporary Workarounds
Disable vulnerable services
allTemporarily disable VPN/AAA virtual servers if not essential
Network segmentation
allRestrict access to NetScaler management interfaces
🧯 If You Can't Patch
- Implement strict network access controls to limit exposure
- Enable enhanced logging and monitoring for exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check NetScaler version and configuration for vulnerable servicesCheck Version:
show versionVerify Fix Applied:
Verify firmware version is patched and no vulnerable configurations remain📡 Detection & Monitoring
Log Indicators:
- Unusual memory access patterns
- Multiple failed authentication attempts
- Suspicious requests to VPN/AAA endpoints
Network Indicators:
- Abnormal traffic to NetScaler management ports
- Memory disclosure patterns in HTTP requests
SIEM Query:
source="netscaler" AND (url="*/vpn/*" OR url="*/aaa/*") AND (status=200 OR status=500) AND size>10000🔗 References
- https://support.citrix.com/support-home/kbsearch/article?articleNumber=CTX693420
- https://citrixbleed.com
- https://horizon3.ai/attack-research/attack-blogs/cve-2025-5777-citrixbleed-2-write-up-maybe/
- https://labs.watchtowr.com/how-much-more-must-we-bleed-citrix-netscaler-memory-disclosure-citrixbleed-2-cve-2025-5777/
- https://www.bleepingcomputer.com/news/security/cisa-tags-citrix-bleed-2-as-exploited-gives-agencies-a-day-to-patch/
- https://www.netscaler.com/blog/news/netscaler-critical-security-updates-for-cve-2025-6543-and-cve-2025-5777/
- https://www.theregister.com/2025/07/10/cisa_citrixbleed_kev/
- https://doublepulsar.com/citrixbleed-2-exploitation-started-mid-june-how-to-spot-it-f3106392aa71
- https://reliaquest.com/blog/threat-spotlight-citrix-bleed-2-vulnerability-in-netscaler-adc-gateway-devices/
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-5777
