Bitcoin Core Reveals Three Vulnerabilities, One of Which Could Disrupt Mining

On November 10, 2026, Bitcoin Core developers published details of three vulnerabilities that were fixed back in the fall of 2025. The most serious of them, CVE-2025-62861, was rated as high risk and could temporarily disrupt the operation of individual mining nodes. Developers do not provide information on the actual exploitation of these vulnerabilities by attackers.

How the vulnerability could affect mining

During blockchain reorganization, the error could lead to incorrect removal of transactions from the mempool – the queue of unconfirmed operations. After this, the node lost the ability to create a correct template for a new block, necessary for the miner's work. The issue was resolved by restarting the program, which restored the consistent state of the mempool. The vulnerability affected Bitcoin Core versions 28.0–28.2 and 29.0–29.1.

What other errors were found in Bitcoin Core

The second error, CVE-2025-62859, allowed a malicious network participant to delay block processing using specially modified compact block data. Under certain conditions, delays could repeat. The third, CVE-2025-62860, affected connections through Tor: in some configurations, the program mistakenly granted incoming connections trusted rights. This weakened the protection of nodes from overload and leakage of service information.

When developers released the fixes

Fixes for all three issues were included in Bitcoin Core 30.0 on October 10, 2025, and 29.2 on October 14. Public descriptions were released on November 10, 2026, after support for the last affected branch ended. None of the vulnerabilities allowed for direct theft of bitcoins or issuance of coins beyond the set limit. Developers recommend that node operators use the current supported versions of the client.