Citrix ADC and Gateway Unauthenticated Remote Code Execution Vulnerability Advisory (CVE-2022-27518)
Executive & SecOps Summary
SECOPS ASSESSMENTCitrix ADC and Citrix Gateway versions 12.1 and 13.0 with SAML SP or IdP configuration enabled
Unauthenticated remote attackers can execute arbitrary code on the target appliance and gain full system control by sending specially crafted requests
Immediately upgrade to the patched firmware versions (12.1-65.25, 13.0-88.16, or higher) provided by Citrix
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Administrators must upgrade the vulnerable Citrix ADC/Gateway appliances to the recommended patched versions immediately. Use the following CLI commands to verify the version and apply the update.
# 1. Check the current Citrix ADC/Gateway version
show ns version
# 2. Extract and run the installer after uploading the patched firmware (e.g., 13.0-88.16)
tar -xvzf build_msg_13.0-88.16_cl.tgz
./installns2. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, restrict access to the SAML endpoints using network-level access control lists (ACLs) or temporarily disable the vulnerable SAML virtual servers.
# Verify existing SAML configurations
show samlAction
show samlIdPProfile
# Temporarily disable the vulnerable SAML virtual server if applicable
disable lb vserver <SAML_Virtual_Server_Name>3. Log Audit & IoC Verification Commands
Run the following commands on the Citrix shell to inspect system logs for potential exploitation attempts or abnormal process crashes.
# Search for SAML-related anomalies in the system log
grep -i 'saml' /var/log/ns.log
grep -i 'segfault' /var/log/messages
# Check for recent core dumps indicating process crashes
ls -la /var/core/Stop Exposing VPN Ports to the Internet — Switch to Zero-Trust Access
Eliminate public-facing VPN concentrators and firewall management ports with identity-first Zero-Trust Network Access.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2022-27518) is a critical resource management and memory corruption flaw (CWE-664) within the SAML (Security Assertion Markup Language) implementation of Citrix ADC and Citrix Gateway. When the appliance is configured as a SAML Service Provider (SP) or a SAML Identity Provider (IdP), it fails to properly validate and handle incoming SAML authentication payloads, leading to an exploitable memory state.
2. Exploitation Mechanics & Attack Scenario
An unauthenticated remote attacker can exploit this vulnerability by sending a maliciously crafted SAML request to the vulnerable Citrix appliance's SAML endpoint. The crafted payload triggers memory corruption within the parsing engine, allowing the attacker to hijack the execution flow of the system process (such as nsppe) and execute arbitrary shell commands or malicious payloads without requiring any user interaction or credentials.
3. Infrastructure & Business Impact
Since Citrix ADC and Gateway function as critical entry points to corporate networks, successful exploitation of this vulnerability allows attackers to establish a persistent foothold. Attackers can deploy backdoors, hijack active VPN sessions, and perform lateral movement to compromise internal network assets. This vulnerability is highly critical and has been actively exploited in the wild, as cataloged in the CISA KEV.
Official Vendor Advisories & References
Unauthenticated remote arbitrary code execution
Frequently Asked SecOps Questions (CVE-2022-27518)
FAQQ1. How critical is CVE-2022-27518 and is it actively exploited in the wild?
CVE-2022-27518 is rated CVSS 9.8 (CRITICAL) with a 30-day EPSS exploitation probability of 6.9%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2022-27518?
Primary impacted vendors include citrix across adc, gateway. Scope summary: Citrix ADC and Citrix Gateway 13.0 (prior to 13.0-88.16) and 12.1 (prior to 12.1-65.25) configured as a SAML SP or SAML IdP
Q3. What temporary mitigations or workarounds exist for CVE-2022-27518 before patching?
[Mitigation] Immediately upgrade to the patched firmware versions (12.1-65.25, 13.0-88.16, or higher) provided by Citrix Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2022-27518
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