CVE-2020-36732 in crypto-js
Summary
by MITRE • 06/12/2023
The crypto-js package before 3.2.1 for Node.js generates random numbers by concatenating the string "0." with an integer, which makes the output more predictable than necessary.
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Analysis
by VulDB Data Team • 11/17/2025
The vulnerability identified as CVE-2020-36732 affects the crypto-js package version 3.2.1 and earlier in Node.js environments, presenting a significant weakness in cryptographic randomness generation that directly impacts security-sensitive applications. This flaw resides in how the package handles random number generation by employing a predictable concatenation method that combines the string "0." with integer values, creating output that lacks the necessary entropy required for robust cryptographic operations. The vulnerability stems from the package's failure to utilize proper cryptographic random number generators that would ensure unpredictable sequences essential for security protocols. This predictable random number generation mechanism represents a deviation from established cryptographic best practices and creates potential attack vectors for adversaries seeking to compromise systems relying on this library.
The technical implementation of this vulnerability manifests through the specific concatenation approach used in the random number generation process, where the string "0." is prepended to integer values to produce what should be random outputs. This methodology fundamentally undermines the cryptographic strength of the generated numbers by creating patterns that can be statistically analyzed and potentially predicted. The flaw directly violates the principles outlined in CWE-330, which addresses the use of insufficiently random values in cryptographic contexts. The predictable nature of these random numbers compromises the integrity of any cryptographic operations that depend on the randomness for security, including but not limited to key generation, nonce creation, and initialization vector construction.
The operational impact of this vulnerability extends beyond simple cryptographic weakness to encompass broader security implications for applications that depend on the crypto-js library for secure operations. Systems utilizing this vulnerable version may experience compromised encryption strength, making them susceptible to various attacks including but not limited to key recovery attacks, replay attacks, and pattern recognition exploits. The vulnerability particularly affects applications that rely on the library for generating secure tokens, cryptographic keys, or other security-critical random values. According to ATT&CK framework category T1083, adversaries may exploit such weaknesses to gather information about system security configurations, potentially leading to more sophisticated attacks. Organizations using vulnerable versions of this library face increased risk of data breaches and unauthorized access attempts that could compromise sensitive information and system integrity.
Mitigation strategies for CVE-2020-36732 require immediate action to upgrade the crypto-js package to version 3.2.1 or later, where the random number generation has been properly implemented to ensure cryptographic strength. Security teams should conduct comprehensive audits of their applications to identify all dependencies on vulnerable versions and implement proper version control measures to prevent future occurrences. Organizations should also consider implementing additional security controls such as regular dependency scanning and vulnerability assessments to identify similar weaknesses in their software supply chains. The remediation process should include thorough testing of applications after upgrading to ensure that the new version maintains expected functionality while providing the necessary cryptographic security. Additionally, organizations should review their development practices to ensure that cryptographic libraries are selected based on established security standards and that proper security reviews are conducted before integrating third-party components into production systems.