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A high-severity vulnerability, identified as CVE-2024-43405, has been discovered in the open-source vulnerability scanner Nuclei. This flaw allows attackers to bypass signature checks and execute arbitrary code by using specially crafted templates. The vulnerability, which carries a CVSS score of 7.4, affects all versions of Nuclei later than 3.0.0. The vulnerability was discovered by Wiz's engineering team and arises from a discrepancy between how signature verification and the YAML parser handle newline characters in combination with how multiple signatures are processed.

This mismatch can be exploited by injecting malicious content into a template while maintaining a valid signature for the benign parts. This allows a bypass of the template integrity verification mechanism. Nuclei utilizes YAML-based templates for vulnerability detection, supporting various protocols and even enabling code execution on the host operating system through the code protocol. Users are strongly advised to update to the latest version, 3.3.7, to mitigate this critical security risk, and were advised of version 3.3.2 as an initial fix. The software is a widely used tool in the security community with over 21,000 Github stars and 2.1M downloads.

ImgSrc: securityaffairs.com

References:

• CISO2CISO.COM & CYBER SECURITY GROUP - Researchers Uncover Nuclei Vulnerability Enabling Signature Bypass and Code Execution – Source:thehackernews.com - 2d
• Security Archives - Security Affairs - Nuclei flaw allows signature bypass and code execution - 2d
• The Hacker News - Researchers Uncover Nuclei Vulnerability Enabling Signature Bypass and Code Execution - 2d
• ciso2ciso.com - Researchers Uncover Nuclei Vulnerability Enabling Signature Bypass and Code Execution – Source:thehackernews.com - 2d
• ciso2ciso.com - Nuclei flaw allows signature bypass and code execution – Source: securityaffairs.com - 2d
• CISO2CISO.COM & CYBER SECURITY GROUP - Nuclei flaw allows signature bypass and code execution – Source: securityaffairs.com - 2d
• @jos1264 - Researchers Uncover Nuclei Vulnerability Enabling Signature Bypass and Code Execution – Source:thehackernews.com - 2d
• Osint10x - Researchers Uncover Nuclei Vulnerability Enabling Signature Bypass and Code Execution - 1d
• CISO2CISO.COM & CYBER SECURITY GROUP - Open source vulnerability scanner found with a serious vulnerability in its own code – Source: www.csoonline.com - 1d
• ciso2ciso.com - Open source vulnerability scanner found with a serious vulnerability in its own code - 22h

Classification:

• HashTags: Vulnerability Nuclei CodeExecution
• Company: ProjectDiscovery
• Target: Nuclei
• Product: Nuclei
• Feature: signature bypass
• Type: Vulnerability
• Severity: Major