What is CVE-2023-6549?

CVE-2023-6549 is a high-severity vulnerability affecting NetScaler ADC and NetScaler Gateway software. This vulnerability allows for unauthenticated denial of service and out-of-bounds memory read, impacting systems running vulnerable versions of the software. Specifically, appliances configured as a Gateway or AAA virtual server are at risk. It is crucial for organizations to update their software to mitigate the potential risks associated with this vulnerability.

Who is impacted?

The CVE-2023-6549 vulnerability affects users of NetScaler ADC and NetScaler Gateway software. Specifically, it impacts NetScaler Application Delivery Controller (ADC) versions from 12.1 up to 12.1-55.302, 13.0 up to 13.0-92.21, 13.1 up to 13.1-51.15, and 14.1 up to 14.1-12.35. It also affects NetScaler Gateway versions from 13.0 up to 13.0-92.21, 13.1 up to 13.1-51.15, and 14.1 up to 14.1-12.35. This vulnerability can lead to unauthenticated denial of service and out-of-bounds memory read, posing a risk to systems running these vulnerable versions.

What to do if CVE-2023-6549 affected you

If you're affected by the CVE-2023-6549 vulnerability, it's crucial to take action to protect your systems. Follow these simple steps:

1. Update your NetScaler ADC and NetScaler Gateway software to the latest versions provided by Citrix.

2. Isolate affected assets from the network to minimize direct access to critical software and data.

3. Implement network segmentation, software-defined perimeters, and proxies for added security.

4. Stay informed about known exploited vulnerabilities and apply mitigations as recommended by vendors.

Is it in CISA’s Known Exploited Vulnerabilities Catalog?

The CVE-2023-6549 vulnerability, also known as the Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability, is indeed present in CISA's Known Exploited Vulnerabilities Catalog. It was added on January 17, 2024, and the due date for required action is February 7, 2024. Organizations must apply mitigations as per vendor instructions or discontinue the use of the product if mitigations are unavailable.

Weakness Enumeration

The weakness enumeration for this vulnerability is categorized as CWE-119, which involves improper restriction of operations within memory buffers.

Learn More

CVE-2023-6549 is a significant vulnerability affecting NetScaler ADC and NetScaler Gateway software, with potential consequences including unauthenticated denial of service and out-of-bounds memory read. For a comprehensive understanding of this vulnerability, including its description, severity, technical details, and known affected software configurations, refer to the NVD page or the sources listed below.

• NetScaler ADC and NetScaler Gateway Security Bulletin for CVE-2023-6548 and CVE-2023-6549

• BOD 22-01: Reducing the Significant Risk of Known Exploited Vulnerabilities | CISA

• Known Exploited Vulnerabilities Catalog