CVE-2022-27518: Citrix ADC Firmware RCE Vulnerability

CVE-2022-27518 Overview

CVE-2022-27518 is a critical unauthenticated remote arbitrary code execution vulnerability affecting Citrix Application Delivery Controller (ADC) and Citrix Gateway appliances. This vulnerability allows threat actors to execute arbitrary code on vulnerable systems without requiring any form of authentication, making it particularly dangerous for internet-facing deployments.

Critical Impact

This vulnerability enables unauthenticated attackers to achieve complete system compromise through remote code execution on Citrix ADC and Gateway appliances, which are commonly deployed at network perimeters as SSL VPN and load balancing solutions.

Affected Products

• Citrix Application Delivery Controller (ADC) Firmware
• Citrix Application Delivery Controller (FIPS and NDCPP configurations)
• Citrix Gateway Firmware
• Citrix Gateway

Discovery Timeline

• December 13, 2022 - CVE-2022-27518 published to NVD
• October 24, 2025 - Last updated in NVD database

Technical Details for CVE-2022-27518

Vulnerability Analysis

CVE-2022-27518 represents a severe remote code execution vulnerability in Citrix ADC and Gateway products. The flaw stems from improper resource lifecycle management (CWE-664), which allows attackers to manipulate system resources in unintended ways. When exploited, an unauthenticated remote attacker can execute arbitrary code with elevated privileges on the underlying system.

The vulnerability is particularly concerning because Citrix ADC and Gateway appliances are typically deployed at network perimeters, serving as SSL VPN endpoints and application delivery controllers. This positioning means vulnerable systems are often directly accessible from the internet, significantly increasing the attack surface and risk of exploitation.

This vulnerability has been confirmed as actively exploited in the wild and is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, indicating that threat actors are actively targeting vulnerable systems.

Root Cause

The root cause of this vulnerability is classified as CWE-664 (Improper Control of a Resource Through its Lifetime). This weakness category encompasses scenarios where software fails to properly manage a resource throughout its lifetime, including improper initialization, use, transfer, or release of resources. In the context of Citrix ADC and Gateway, this improper resource control creates conditions that attackers can exploit to achieve arbitrary code execution without authentication.

Attack Vector

The attack vector for CVE-2022-27518 is network-based, requiring no authentication, user interaction, or special privileges. Attackers can remotely target vulnerable Citrix ADC and Gateway systems directly over the network.

Exploitation typically involves sending specially crafted requests to vulnerable Citrix appliances. The attack does not require the attacker to have any existing credentials or session on the target system. Given that these appliances are designed to be internet-accessible for remote access purposes, the attack surface is significant.

The vulnerability affects systems configured as SAML SP (Service Provider) or SAML IdP (Identity Provider), which is a common deployment configuration for enterprise environments using federated authentication.

Detection Methods for CVE-2022-27518

Indicators of Compromise

• Unexpected processes spawned by Citrix ADC/Gateway web server components
• Anomalous outbound network connections from Citrix appliances to unknown IP addresses
• Suspicious files or scripts appearing in Citrix system directories
• Unusual authentication attempts or SAML-related log entries

Detection Strategies

• Monitor Citrix ADC and Gateway appliances for unexpected process execution or child processes
• Implement network-based intrusion detection rules for anomalous traffic patterns to Citrix management interfaces
• Review system logs for signs of exploitation including unusual crashes, restarts, or service disruptions
• Deploy endpoint detection and response (EDR) solutions on network segments adjacent to Citrix appliances

Monitoring Recommendations

• Enable comprehensive logging on all Citrix ADC and Gateway appliances
• Configure SIEM alerts for authentication anomalies and unexpected administrative actions
• Monitor for indicators of lateral movement originating from Citrix appliance network segments
• Regularly audit SAML configuration settings and federation trust relationships

How to Mitigate CVE-2022-27518

Immediate Actions Required

• Immediately identify all Citrix ADC and Gateway appliances in your environment
• Verify current firmware versions against the vulnerable version list in the Citrix security advisory
• Apply security patches from Citrix as the highest priority remediation action
• If patching is not immediately possible, consider temporarily disabling SAML authentication functionality

Patch Information

Citrix has released security patches to address this vulnerability. Organizations should refer to Citrix Support Article CTX474995 for detailed patch information and affected version matrices. Given the active exploitation of this vulnerability and its inclusion in the CISA Known Exploited Vulnerabilities catalog, immediate patching is strongly recommended.

Workarounds

• If immediate patching is not possible, disable SAML SP and SAML IdP functionality on affected appliances as a temporary measure
• Implement network segmentation to limit access to Citrix management interfaces
• Deploy web application firewall (WAF) rules to filter potentially malicious requests
• Consider temporary service suspension for internet-facing vulnerable appliances until patches can be applied

# Verify Citrix ADC/Gateway firmware version
# Connect to the Citrix ADC CLI and run:
show version

# Check SAML configuration status
show authentication samlAction