Blockchain Security: Threats, Vulnerabilities and Countermeasures − A Review

Manav Rachna International Institute of Research and Studies, India
* Corresponding author. Email: kshitijray028@gmail.com (K.K.)
Manuscript received July 24, 2025; Accepted September 30, 2025; published November 4, 2025.

Abstract—The decentralized, transparent, and immutable ledger system of blockchain has fundamentally changed data security and digital transactions. Blockchain has built-in security safeguards, yet it is still vulnerable to flaws and attacks. In this review paper, the authors will examine the threats and vulnerabilities that blockchain technology faces and the mitigation factors that can be used to overcome these issues. The authors discuss the significant threats like the 51% attack, double spending attack and many more that compromise the integrity of blockchain technology further authors discuss the vulnerabilities that are present in consensus mechanisms, smart contracts, network level, cryptography and privacy. These vulnerabilities expose blockchain networks to potential exploits and operational risks. To overcome these threats and challenges, the paper also discusses several countermeasures that are used for strengthening the blockchain network. It includes consensus mechanism enhancement through hybrid models and enhancing network-level protection against DDoS and routing attacks. This paper also discusses about the significance of quantum resistance cryptographic algorithms, privacy-enhancing technologies like zero-knowledge proofs, and scalability solutions such as layer 2 protocols and sidechains. This review paper also includes the current research and advancements in security blocks and provides a detailed understanding of the present work and future initiatives in the blockchain system.

Keywords—blockchain security, decentralization, threats, cryptography, privacy enhancing technologies, scalability, mitigation factors

Cite: Kshitij Kumar, Dhiraj Kumar, Shivam Baghel, and Kavita Arora, "Blockchain Security: Threats, Vulnerabilities and Countermeasures − A Review," International Journal of Blockchain Technologies and Applications vol. 3, no. 2, pp. 138-145, 2025.

Copyright © 2025 by the authors. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0)