NetScaler ADC Vulnerabilities - Urgent Patches Released

The Flaw

Cloud Software Group has identified two critical vulnerabilities in NetScaler ADC and NetScaler Gateway. The first, CVE-2026-3055, has a CVSS score of 9.3, indicating its critical nature. This vulnerability arises from insufficient input validation, leading to an out-of-bounds read condition. Essentially, this means that an attacker could potentially read sensitive data from memory without needing to authenticate. The second vulnerability, CVE-2026-4368, scores 7.7 and involves a race condition that could result in user session mix-ups, posing serious risks in environments using VPNs.

Both vulnerabilities require specific configurations to be exploitable. For CVE-2026-3055, the affected appliance must be set up as a SAML Identity Provider (IDP). Meanwhile, CVE-2026-4368 affects appliances configured as a Gateway or AAA virtual server. The potential for unauthorized access makes these vulnerabilities particularly dangerous.

What's at Risk

Organizations using affected versions of NetScaler ADC and Gateway are at significant risk. The vulnerabilities could allow unauthenticated remote attackers to compromise systems, leading to unauthorized access and data breaches. Given the widespread use of NetScaler products in enterprise environments, the attack surface is substantial. If left unpatched, these vulnerabilities could lead to severe consequences, including data loss and reputational damage.

The vulnerabilities impact various versions of the software, including NetScaler ADC/Gateway 14.1 before 14.1-66.59 and 13.1 before 13.1-62.23. Organizations must check their configurations to determine if they are vulnerable and take immediate action.

Patch Status

In response to these vulnerabilities, Cloud Software Group has released urgent security patches. Organizations are advised to upgrade to the following fixed releases:

• NetScaler ADC and Gateway 14.1-66.59 or later
• NetScaler ADC and Gateway 13.1-62.23 or later
• NetScaler ADC 13.1-FIPS / NDcPP 13.1.37.262 or later

It’s crucial to note that this advisory applies specifically to customer-managed deployments. Citrix-managed cloud services have already been updated, reducing the risk for those users. Administrators should prioritize applying these patches to mitigate the risk of exploitation.

Immediate Actions

To protect your organization, follow these steps:

1. Check your version of NetScaler ADC and Gateway against the affected versions.
2. Review your configurations to see if you are using SAML IDP or Gateway settings.
3. Apply the recommended patches immediately to secure your systems.
4. Monitor your systems for any signs of unusual activity following the patching process.

By taking these actions, organizations can significantly reduce their risk of falling victim to these vulnerabilities. Given the critical nature of CVE-2026-3055, swift action is essential to safeguard sensitive data and maintain operational integrity.