High-Severity Vulnerability Discovered in Nuclei Vulnerability Scanner: Exploitation Risks and Mitigation Strategies

High-Severity Flaw Discovered in Nuclei Vulnerability Scanner, Potentially Exposing Sensitive Data

Jan 04, 2025 — A critical security vulnerability has been identified in Nuclei, an open-source vulnerability scanner widely utilized for assessing the security of applications, infrastructure, and cloud platforms. The flaw, designated CVE-2024-43405, boasts a CVSS score of 7.4, highlighting its serious implications if exploited.

Discovered by cloud security firm Wiz, the vulnerability revolves around issues in the template signature verification process. This process is intended to validate the integrity of templates used by Nuclei, which operate on the YAML file format. However, a misalignment between how signature checks and the YAML parser process newline characters can enable attackers to inject malicious content while retaining a seemingly valid signature.

Wiz researcher Guy Goldenberg explained that attackers can exploit this flaw by introducing a "\r" character, tricking the parser into executing harmful code that would otherwise be filtered out. This inconsistency creates a perilous scenario where unauthorized templates can be executed on a host system, potentially leading to data breaches or total system compromise.

The vulnerability primarily arises when organizations employ untrusted or community-contributed templates without adequate validation measures. Goldenberg cautioned, “An attacker could exploit this functionality to inject malicious templates, leading to arbitrary command execution and critical data exfiltration.”

In response to the threat, ProjectDiscovery addressed the vulnerability on September 4, 2024, with a crucial update to version 3.3.2, with the current version now at 3.3.7. Users are urged to upgrade immediately and validate templates rigorously to mitigate the risk of exploitation. As cyber threats continue to evolve, vigilance and proactive security measures remain paramount.