CVE-2018-17144: A Critical Denial of Service Vulnerability in Bitcoin Core and Its Implications for Blockchain Security

BY KEYHUNTER 03.04.2025

The vulnerability CVE-2018-17144 in Bitcoin Core software, classified as a Denial of Service (DoS) issue, posed significant risks to the Bitcoin network and related cryptocurrencies. This bug allowed attackers to crash unpatched Bitcoin nodes by sending malformed transactions that attempted to spend the same input twice. While initially disclosed as a DoS bug, further analysis revealed it could also lead to inflation vulnerabilities, enabling double-spending under specific conditions[1][4][6].

Key Details:

  1. Impact on Bitcoin Core: The bug affected Bitcoin Core versions 0.14.0 through 0.16.2, released between March 2017 and September 2018. It was patched in version 0.16.3[3][4][6].
  2. Exploitation Risks: Attackers could remotely crash nodes, potentially facilitating a 51% attack—a scenario where malicious actors gain control over the majority of network mining power to manipulate transactions[3][5].
  3. Broader Implications: Cryptocurrencies forked from Bitcoin’s code, such as Litecoin, were also vulnerable until patched. Smaller cryptocurrencies faced heightened risks due to weaker networks and delayed fixes[3][6].
  4. Response and Mitigation: The vulnerability was responsibly disclosed on September 17, 2018, with patches released within days. Most full nodes upgraded promptly, preventing exploitation on Bitcoin’s mainnet[1][6].

Summary:

CVE-2018-17144 highlighted critical security challenges in blockchain systems, emphasizing the need for timely updates and proactive communication among cryptocurrency projects to mitigate risks effectively. While Bitcoin’s main network remained secure, smaller cryptocurrencies demonstrated greater susceptibility due to delayed patching and lower network resilience[3][6].

The CVE-2018-17144 bug affected Bitcoin nodes by exploiting a flaw in Bitcoin Core software versions 0.14.0 to 0.16.2, allowing attackers to crash nodes and potentially disrupt the network. Here’s how it specifically impacted Bitcoin nodes:

Effects on Bitcoin Nodes:

  1. Denial of Service (DoS): The bug allowed attackers to crash Bitcoin Core nodes remotely by sending malformed transactions that attempted to spend the same input twice. This triggered an assertion failure in the node software, causing it to crash intentionally[1][3][4].
  2. Inflation Risk: In addition to crashing nodes, the bug could theoretically allow malicious miners to double-spend bitcoins, artificially inflating the supply. This was due to a skipped validation check introduced in Bitcoin Core 0.14.0, which allowed duplicate inputs in transactions[3][6].
  3. Facilitation of 51% Attacks: By crashing enough nodes, attackers could reduce the cost of executing a 51% attack—a scenario where they gain control over the majority of mining power and manipulate transactions for financial gain[1][4].
  4. Testnet Exploitation: While the bug was never exploited on the Bitcoin mainnet, it was successfully exploited on the testnet after disclosure, demonstrating its potential impact on non-upgraded nodes[3].
  5. Affected Versions: The vulnerability impacted all Bitcoin Core versions released between March 2017 and September 2018 (0.14.x through 0.16.x), as well as Bitcoin Knots software based on the same code[1][4].

Mitigation:

The bug was patched in Bitcoin Core version 0.16.3 within days of its discovery in September 2018, preventing exploitation on the main network[3][6]. Users were advised to upgrade immediately to avoid risks.

Summary:

CVE-2018-17144 posed a severe threat to Bitcoin nodes by enabling remote crashes and potential double-spending vulnerabilities. While timely patches prevented exploitation on the main network, the incident highlighted critical risks in blockchain security and underscored the importance of rapid updates and proactive vulnerability management[1][3][6].

The Bitcoin Core team responded swiftly and effectively to the discovery of the CVE-2018-17144 bug, taking several key steps to mitigate its impact:

  1. Immediate Fix: The team quickly developed and released a patch for the bug in Bitcoin Core version 0.16.3. This update ensured that nodes would reject any blocks containing malformed transactions that could exploit the vulnerability[1][2].
  2. Responsible Disclosure: Initially, the team kept the full details of the vulnerability confidential to prevent exploitation. They focused on getting nodes and miners to update to the patched version as quickly as possible[1].
  3. Coordination with the Ecosystem: The Bitcoin Core Development Team worked closely with other stakeholders in the Bitcoin ecosystem, including miners and exchanges, to ensure a rapid update to the patched software. This coordination was crucial in preventing exploitation before most of the network upgraded[1].
  4. Post-Patch Disclosure: Once enough nodes had upgraded and the immediate risk had passed, the team disclosed the full details of the bug to the public. This included a thorough explanation of how the bug could have been exploited and the steps taken to fix it[1].

Overall, the Bitcoin Core team’s prompt and coordinated response effectively mitigated the risks associated with CVE-2018-17144, protecting the integrity of the Bitcoin network.

The Bitcoin Core security team played a crucial role in addressing the CVE-2018-17144 bug by taking several key steps:

  1. Initial Response and Identification: An anonymous developer discovered the bug and reported it to the Bitcoin Core security team, who quickly identified it as a serious vulnerability. This swift identification was crucial in preventing potential exploitation[2].
  2. Patch Development: The team rapidly developed a patch to fix the bug, which was released as part of Bitcoin Core version 0.16.3. This update ensured that nodes would reject any blocks containing malformed transactions that could exploit the vulnerability[2].
  3. Responsible Disclosure: The team initially kept the full details of the vulnerability confidential to prevent exploitation. They focused on getting nodes and miners to update to the patched version as quickly as possible, minimizing the risk of exploitation[2].
  4. Coordination with the Ecosystem: The Bitcoin Core Development Team worked closely with other stakeholders in the Bitcoin ecosystem, including miners and exchanges, to ensure a rapid update to the patched software. This coordination was crucial in preventing exploitation before most of the network upgraded[2].
  5. Post-Patch Disclosure: Once enough nodes had upgraded and the immediate risk had passed, the team disclosed the full details of the bug to the public, including a thorough explanation of how the bug could have been exploited and the steps taken to fix it[2].

The Bitcoin Core security team’s proactive and coordinated response effectively mitigated the risks associated with CVE-2018-17144, protecting the integrity of the Bitcoin network.

In the aftermath, the team also acknowledged the need for better transparency in disclosing security vulnerabilities, which led to the development of a new policy aimed at improving communication about critical bugs[3][4][5].

Citations:
[1] https://cryptoslate.com/bitcoin-core-dev-takes-responsibility-for-critical-bug-im-embarrassed-and-sorry/
[2] https://www.ark-invest.com/articles/analyst-research/supporting-the-unsung-heroes-of-bitcoin
[3] https://unchainedcrypto.com/perception-that-bitcoin-core-never-has-bugs-dangerous-say-developers/
[4] https://defi-planet.com/2024/07/bitcoin-core-developers-introduce-new-critical-bug-disclosure-policy-to-enhance-security-communication/
[5] https://bitcoinnews.com/adoption/bitcoin-core-new-policy-bugs/
[6] https://coinspaidmedia.com/news/bitcoin-developers-reveal-bitcoin-vulnerabilities/
[7] https://osl.com/en/academy/article/bitcoin-core-explained-what-it-is-and-whos-in-charge
[8] https://groups.google.com/g/bitcoindev/c/Q2ZGit2wF7w

Citations:
[1] https://www.ark-invest.com/articles/analyst-research/supporting-the-unsung-heroes-of-bitcoin
[2] https://www.cyberdefensemagazine.com/bitcoin-core-team-fixes-a-critical-ddos-flaw-in-wallet-software/
[3] https://github.com/bitcoin-core/meta/issues/5
[4] https://www.zdnet.com/article/researcher-kept-a-major-bitcoin-bug-secret-for-two-years-to-prevent-attacks/
[5] https://bitcointalk.org/index.php?topic=5032831.0
[6] https://www.reddit.com/r/Bitcoin/comments/76v747/bitcoin_core_code_was_tested_so_thoroughly_that/
[7] https://www.coindesk.com/ru/tech/2020/09/09/high-severity-bug-in-bitcoin-software-revealed-2-years-after-fix
[8] https://www.nasdaq.com/articles/this-security-researcher-found-the-bug-that-knocked-out-bitcoin-unlimited-2017-03-15

Citations:
[1] https://www.zdnet.com/article/bug-in-bitcoin-code-also-opens-smaller-cryptocurrencies-to-attacks/
[2] https://cointelegraph.com/news/the-anatomy-of-bitcoin-cores-recent-bug
[3] https://bitcoinops.org/en/topics/cve-2018-17144/
[4] https://www.cvedetails.com/cve/CVE-2018-17144/
[5] https://security-tracker.debian.org/tracker/CVE-2018-17144
[6] https://hackernoon.com/bitcoin-core-bug-cve-2018-17144-an-analysis-f80d9d373362
[7] https://bitcoincore.org/en/2018/09/20/notice/
[8] https://www.suse.com/security/cve/CVE-2018-17144.html

Citations:
[1] https://bitcoinops.org/en/topics/cve-2018-17144/
[2] https://cve.mitre.org/cgi-bin/cvekey.cgi
[3] https://www.zdnet.com/article/bug-in-bitcoin-code-also-opens-smaller-cryptocurrencies-to-attacks/
[4] https://www.cvedetails.com/cve/CVE-2018-17144/
[5] https://hackernoon.com/bitcoin-core-bug-cve-2018-17144-an-analysis-f80d9d373362
[6] https://bitcoincore.org/en/2018/09/20/notice/
[7] https://www.livebitcoinnews.com/cve-2018-17144-the-aftermath-of-a-catastrophic-bitcoin-bug/
[8] https://www.suse.com/security/cve/CVE-2018-17144.html