Bitcoin Core Discloses Three Patched Security Flaws That Could Have Frozen Mining Nodes

Bitcoin Core developers have publicly disclosed three security vulnerabilities reported during 2025 and patched in October 2025, with the project holding back details until its last vulnerable release line, version 29.x, reached end of life on October 27. The disclosures cover denial-of-service and privacy issues rather than any risk of coin theft.

The most serious is a high-severity flaw triggered during chain reorganizations that corrupted a node's mempool by removing transactions without clearing their related descendants. This left affected nodes holding transactions that spent unavailable outputs, causing block template construction to fail validity checks and preventing miners from building new blocks entirely. The fix, according to developers, amounts to restarting the node.

Two medium-severity issues round out the disclosure. One caused block-processing delays, and the other inadvertently granted whitelist permissions to certain Tor connections. All three bugs have been patched, but nodes running older software remain at risk, and developers have used the disclosure to urge operators to update promptly.