Bitcoin Core Reveals Three Security Flaws That Threatened Mining and Node Operations

Bitcoin Core developers have disclosed three security vulnerabilities that exposed Bitcoin nodes to mining disruptions, delayed block processing, and weakened network protections.

According to security advisories published on November 10, developers patched the vulnerabilities in October 2025, before publicly revealing their technical details. The disclosures cover one high-severity flaw and two medium-severity weaknesses affecting different Bitcoin Core versions and network configurations.

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High-Severity Bitcoin Core Bug Disrupted Mining Operations

The most serious vulnerability, CVE-2025-62861, affected Bitcoin Core versions 28.0 through 28.2 and versions 29.0 through 29.1. Security researcher Niklas Goegge identified the weakness on September 26, 2025, uncovering a transaction handling problem during blockchain reorganizations.

Specifically, Bitcoin Core incorrectly applied transaction eviction rules when previously confirmed transactions returned to the network’s memory pool. This behavior could remove transactions while leaving dependent transactions behind, creating inconsistencies that prevented miners from generating valid block templates.

Affected mining nodes required a software restart to restore normal operations, making the vulnerability particularly significant for mining infrastructure.

Additional Vulnerabilities Exposed Bitcoin Nodes to Processing Delays and Privacy Risks

Another vulnerability, CVE-2025-62859, allowed malicious peers to manipulate transaction witness data and delay Bitcoin block processing by ten minutes. Researcher Eugene Siegel reported the medium-severity weakness in April 2025, identifying risks involving compact blocks and certain network configurations.

Attackers could repeatedly exploit affected nodes operating in blocksonly mode or controlling connections to all three high-bandwidth peers. Meanwhile, CVE-2025-62860 exposed a separate configuration weakness involving Tor connections and Bitcoin Core’s optional whitelist settings.

Affected nodes could mistakenly grant incoming Tor peers elevated permissions, bypassing certain denial-of-service restrictions and privacy safeguards. Bitcoin Core estimated that thousands of reachable mainnet nodes had configurations granting whitelist privileges to incoming Tor connections.

Bitcoin Core Confirms Security Fixes Across Software Releases

Bitcoin Core developers addressed all three vulnerabilities through version 30.0, released on October 10, 2025. Additionally, version 29.2 introduced corresponding security fixes on October 14, providing another patched option for affected node operators.

The final vulnerable Bitcoin Core version reached its end-of-life date on October 27, 2026, according to the published advisories. These disclosures follow another high-severity memory safety vulnerability that developers patched before publicly revealing its technical details in May 2026.

The advisories identify affected software versions and document security fixes covering mining reliability, block processing, and network access protections.