Vulnerability Analysis Report [CVE-2025-7775] – Citrix NetScaler

Vulnerability: Citrix NetScaler — Memory OverflowCVE ID: CVE-2025-7775
Date Published: 26 Aug 2025
Severity:Critical
Status:Actively Exploited (CISA KEV Listing)
Vendor: Citrix (NetScaler Gateway / ADC)

Summary

A memory overflow vulnerability has been identified in Citrix NetScaler (formerly Citrix ADC and Gateway). This flaw allows an attacker to trigger uncontrolled memory overwrite, leading to remote code execution (RCE) or denial-of-service (DoS) on affected appliances.

The vulnerability is significant because NetScaler appliances are often internet-facing and serve as secure application delivery controllers, VPN gateways, and identity/SSO entry points. Compromise here can directly expose enterprises to full network infiltration.

Attack Vector

Trigger: Specially crafted packets sent to vulnerable NetScaler services.
Type: Memory Overflow (stack/heap overwrite).
Impact: Potential RCE with system privileges or forced crash/reboot (DoS).
Exposure: High — devices are commonly public-facing in enterprise and government networks.
Exploitation: Confirmed in the wild, as per CISA KEV inclusion.

Impact

Confidentiality: High — adversaries may execute arbitrary code, steal credentials/sessions, or implant persistent backdoors.
Integrity: High — attackers can tamper with data in transit or modify system configurations.
Availability: High — service crashes can disrupt VPN and app delivery infrastructure.

Sectors at risk:

Government, finance, healthcare, manufacturing, and large enterprise networks relying on NetScaler for remote access.

Mitigation & Patching

Vendor Fixes: Apply the latest Citrix NetScaler firmware/hotfix released Aug 26–27, 2025.
Immediate Workarounds:
- Restrict management plane access (only internal trusted IPs).
- Place NetScaler behind reverse proxy/WAF with strict rule sets.
- Enable IDS/IPS signatures for memory overflow exploit patterns.
- Monitor for anomalous crashes, unexplained restarts, and new/unauthorized scheduled tasks.

Detection & Hunting Guidance

Indicators of Exploitation (IoE):
- Unexpected NetScaler process terminations (nsppe, aaad, vpn modules).
- Logs showing malformed packet requests or unknown opcodes.
- Presence of suspicious scripts in /var/netscaler/logon/ or /var/tmp/.
- Spikes in network traffic to VPN/AAA endpoints.
Detection Tools:
- Use EDR/XDR with memory overflow alerts.
- Deploy Suricata/Snort rules tuned to NetScaler overflow exploit attempts.
- Monitor CISA KEV feed & Citrix advisories for ongoing IoCs.

Risk Rating

CVSS v3.x Score (estimated): 9.8 (Critical)
Exploitability: High (public exploitation confirmed)
Impact Score: High

References

CISA KEV: CVE-2025-7775 — Added 26 Aug 2025, actively exploited
Citrix Security Bulletin (Aug 2025) — Patch guidance
Industry advisories from Tenable, SOC Prime, VulDB

Patch immediately. Treat this as priority-0 remediation.
Unpatched NetScaler appliances are prime targets for ransomware crews and APT actors. Apply vendor fixes, harden access controls, and perform forensic review if compromise is suspected.

Author: CyberDudeBivash
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