Bitcoin Core Completes First Public Security Audit

Bitcoin Core, the broadly used software implementation of the Bitcoin protocol, has undergone its first-ever public third-party security audit. The assessment found no high-impact vulnerabilities and introduced new testing tools that strengthen the network’s long-term resilience.

Independent Audit Strengthens Bitcoin Core’s Security

Bitcoin Core, the widely used software running the world’s largest blockchain, has completed its first publicly available third-party security audit. The review was conducted by cybersecurity firm Quarkslab, funded by Brink, and coordinated by the Open Source Technology Improvement Fund (OSTIF). The engagement marks a major milestone for Bitcoin’s security lifecycle, providing an independent examination of software that secures trillions of dollars in value.

Bitcoin Core has evolved significantly since 2009, with more than 46,000 commits and contributions from dozens of developers. Despite its maturity, the project had never undergone a full public audit from an external firm, an absence this review aimed to address.

Conducted between May and September, the audit focused primarily on the peer-to-peer networking layer, one of Bitcoin’s highest-exposure attack surfaces. From there, Quarkslab extended its analysis into mempool logic, chain management, consensus validation, and transaction-handling pathways. The team used a combination of manual code review, dynamic analysis, and advanced fuzzing techniques, some newly introduced to the Bitcoin Core codebase.

The findings were reassuring: auditors identified two low-severity issues and 13 informational recommendations, none of which carried security impact under Bitcoin Core’s internal vulnerability classifications.

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Quarkslab noted that Bitcoin Core’s architecture and code quality demonstrate “outstanding work.” In addition, modern fuzzing approaches like Brink’s ongoing Fuzzamoto initiative could uncover even deeper edge cases in future testing cycles.

The full report and supporting artifacts are publicly available in Quarkslab’s repositories, marking a new era of transparency for Bitcoin’s most critical software.

FAQ 🔍

• Why was this audit important?
  It provides independent verification of Bitcoin Core’s security and robustness.
• Were any major vulnerabilities discovered?
  The assessment didn’t find any high-impact issues.
• Who funded and coordinated the audit?
  Brink funded it, and OSTIF coordinated the engagement.
• What parts of Bitcoin Core were reviewed?
  Mainly the P2P layer, plus mempool, consensus, and chain-management logic