Security Update: Nuclei Vulnerability CVE-2023-37896


Last week, a critical security vulnerability, identified as CVE-2023-37896, surfaced within the Nuclei project – a potent vulnerability scanner renowned for pinpointing security weaknesses. In this comprehensive blog post, we delve into the intricacies of this vulnerability, discuss its potential implications, and outline the steps users must take to safeguard their systems.

Understanding the Vulnerability:

The vulnerability, formally designated as CVE-2023-37896, casts a shadow over Nuclei versions predating 2.9.9. Users who employed Nuclei as Go code (SDK) to execute custom templates were exposed to potential risks. It’s essential to note that this issue remained confined to SDK users, sparing those utilizing the Command Line Interface (CLI). The crux of the vulnerability lies in the sanitization process of payloads during their load in sandbox mode.

Vulnerability Mitigation and Enhancement:

In response, the developers of Nuclei promptly addressed this security lapse in version 2.9.9. Moreover, a proactive measure was introduced wherein sandbox mode is now enabled by default for filesystem loading. This proactive step fortifies the security stance. For users desiring greater flexibility, the option to disable the sandbox mode remains available.

Enhanced User Control and Deprecated Options:

In a bid to empower users with granular control over their Nuclei setups, the now-deprecated -sandbox option has undergone a transformation. It has been replaced by two new options: -lfa (allow local file access) and -lna (restrict local network access). By default, -lfa facilitates file (payload) access throughout the system, effectively bypassing the sandbox constraints. Conversely, -lna is designed to thwart connections to local or private networks.

Swift Response and Version Update:

Project Discovery exhibited remarkable agility in addressing this vulnerability. Swift remediation efforts were undertaken, culminating in the release of Nuclei version 2.9.9. This update stands as a testament to their commitment to user safety. Furthermore, it’s noteworthy that Project Discovery has continued its diligent efforts by launching Nuclei version 2.9.10, which features not only critical fixes but also introduces new functionalities.

Recommended Actions for Users:

To ensure the security of your infrastructure, it’s imperative to adhere to the following guidelines:

  1. Update: Without delay, upgrade your Nuclei installation to the latest release, v2.9.9. This version boasts the crucial security fix for CVE-2023-37896, providing the most effective safeguard against potential risks.
  2. Configuration Review: If your utilization of Nuclei involves Go code (SDK) for custom templates, conduct a meticulous review of your configurations. Align them with the alterations introduced in version 2.9.9. Consider the implications of enabling or disabling sandbox mode, tailoring your choices to your specific requirements.
  3. Stay Informed: Maintain a vigilant watch over trusted sources such as the Nuclei project’s GitHub repository and official security advisories. This vigilance ensures you remain well-informed about crucial updates and potential vulnerabilities, contributing to the maintenance of a secure environment.