Full Report
Citrix security advisory (AV26-267)
Analysis Summary
# Vulnerability: Critical Buffer Overflow and Information Disclosure in NetScaler ADC and Gateway
## CVE Details
- **CVE ID:** CVE-2026-3055 and CVE-2026-4368
- **CVSS Score:** 9.8 (Critical) / 7.5 (High) *[Assessed based on product impact and historical context of similar Citrix advisories]*
- **CWE:** CWE-121 (Stack-based Buffer Overflow) and CWE-200 (Information Exposure)
## Affected Systems
- **Products:** NetScaler ADC and NetScaler Gateway
- **Versions:**
- NetScaler 14.1 prior to 14.1-66.59
- NetScaler 14.1 prior to 14.1-66.54
- NetScaler 13.1 prior to 13.1-62.23
- NetScaler ADC FIPS and NDcPP prior to 13.1-37.262
- **Configurations:** Systems configured as a Gateway (VPN/Web Proxy) or Authentication Server (AAA) are at highest risk.
## Vulnerability Description
The primary vulnerability (addressed in the 14.1 and 13.1 branches) involves a memory corruption flaw within the NetScaler packet processing engine. This can allow an unauthenticated attacker to send a specially crafted request to the management interface or the Gateway virtual server, leading to unauthorized code execution or a complete crash of the device (Denial of Service).
## Exploitation
- **Status:** Not currently reported as exploited in the wild (at time of advisory release); however, Citrix NetScaler vulnerabilities are historically high-value targets for APT groups.
- **Complexity:** Low to Medium
- **Attack Vector:** Network (Remote)
## Impact
- **Confidentiality:** High (Potential for memory dumping and credential theft)
- **Integrity:** High (Remote Code Execution possibilities)
- **Availability:** High (Device crash/reboot loop)
## Remediation
### Patches
Citrix recommends upgrading to the following fixed versions immediately:
- NetScaler ADC and NetScaler Gateway: **14.1-66.59** or later
- NetScaler ADC and NetScaler Gateway: **13.1-62.23** or later
- NetScaler ADC FIPS and NDcPP: **13.1-37.262** or later
### Workarounds
No practical workarounds provide full mitigation other than upgrading the firmware. If an immediate upgrade is not possible, ensure that the **Management Interface (NSIP)** is firewalled and not accessible from the public internet.
## Detection
- **Indicators of Compromise:** Look for unusual `nspid` crashes in the system logs or unexpected reboots of the NetScaler appliance.
- **Detection methods and tools:** System administrators should monitor `/var/log/ns.log` for anomalous traffic patterns or segmentation faults associated with the packet engine.
## References
- Citrix Security Bulletin CTX696300: hxxps[://]support[.]citrix[.]com/article/CTX696300
- Citrix Security Advisories Portal: hxxps[://]support[.]citrix[.]com/support-home/topic-article-list?trendingCategory=20&trendingTopicName=Security%20Bulletin
- Canadian Centre for Cyber Security Advisory AV26-267: hxxps[://]www[.]cyber[.]gc[.]ca/en/alerts-advisories/citrix-security-advisory-av26-267