CVE-2025-62861: Bitcoin Core Mining Bug and 2 More Flaws
Bitcoin Core patches high-severity mining bug CVE-2025-62861 affecting versions 28.0–29.1.
Bitcoin Core disclosed three security flaws patched in October 2025, including CVE-2025-62861, a high-severity bug causing mining nodes to fail block template creation after chain reorganization until restart. The flaw affects Bitcoin Core 28.0–28.2 and 29.0–29.1; during a reorg, the mempool could become corrupted when sibling eviction logic ran on restored transactions. Two additional medium-severity flaws were also disclosed: CVE-2025-62859 allowing malicious peers to stall block processing, and CVE-2025-62860 granting trusted-peer permissions to anonymous Tor connections on nodes with the -whitelist option.
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The lesson from this incident
Full lessonThree security vulnerabilities in Bitcoin Core—spanning versions 28.0 through 29.1—were patched in October 2025, with the most severe (CVE-2025-62861) capable of causing mining nodes to halt block template creation after a chain reorganization until manually restarted. The mempool corruption triggered by sibling eviction logic during reorgs represents a subtle but high-impact software defect that could disrupt mining operations and network stability. Additionally, CVE-2025-62860 exposed a misconfiguration risk where anonymous Tor connections could inadvertently inherit trusted-peer permissions via the -whitelist option. These flaws matter because Bitcoin infrastructure underpins significant financial value, and even brief disruptions to mining nodes or block propagation can have outsized economic and network-integrity consequences. Node operators running affected versions who delayed patching remained exposed to denial-of-service and privilege escalation scenarios during this window.
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Indicators of Compromise
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- cve — CVE-2025-62861
- cve — CVE-2025-62859
- cve — CVE-2025-62860