Bitcoin Core Mining Node Fix: Turn It Off and On Again

What Happened to BitcoinBTC-0.69% Core? The Tech Glitch Explained Simply

Have you ever faced a computer issue where the best solution was turning it off and on again?

That exact situation recently applied to critical machines running the Bitcoin network.

Bitcoin Core developers published details about a high-severity bug that could freeze a mining node.

The flaw prevented affected nodes from building new blocks for miners.

Fortunately, developers patched the problem over a year ago.

However, older nodes that haven't updated may still face operational risks.

Understanding Mempools, Block Templates, and Chain Reorgs

To understand this glitch, it helps to review a few core blockchain concepts.

First, consider the mempool.

Think of the mempool as a waiting room for transactions.

When you send Bitcoin, your transaction sits in this waiting room until a miner picks it up.

Next comes the block template.

A block template acts like a chef's draft menu for the next block.

A node collects pending transactions from the mempool and builds this template.

Miners then attempt to solve the mathematical puzzle for that specific template.

Without a valid block template, a mining node cannot produce new blocks.

Finally, we have chain reorganizations, or reorgs.

Sometimes, two miners find a block at almost the exact same time.

The network temporarily splits into two paths until one becomes longer.

When the longer chain takes over, the network discards the shorter path.

The node must then return transactions from the dropped block back to the waiting room.

The Bug Mechanics: CVE-2025-62861 and Sibling Eviction

On November 10, 2026, the Bitcoin Core project published an advisory for CVE-2025-62861.

The issue involved TRUC transactions, which stands for Topologically Restricted Until Confirmation.

TRUC rules limit transaction chains to prevent network clogging by allowing only one unconfirmed child transaction.

In version 28.0, developers added a feature called sibling eviction.

Sibling eviction lets a newer child transaction paying higher fees replace an older one.

This rule worked well during normal operations but failed during chain reorganizations.

When restoring transactions from a disconnected block, the node dropped a parent transaction.

However, the node mistakenly kept the child transaction.

This created orphan transactions attempting to spend funds that no longer existed.

"Disclosure of the details of a mempool inconsistency due to TRUC 'sibling eviction' rules firing on reorg. A fix was released on October 10th 2025 in Bitcoin Core v30.0. Affected versions are 28.0 to 28.2 and 29.0 to 29.1." — Bitcoin Core Project (@bitcoincoreorg) November 10, 2026

Summary of Technical Vulnerability Details

• Affected Versions: Bitcoin Core 28.0 to 28.2 and 29.0 to 29.1.
• Root Cause: Misbehavior of TRUC sibling eviction rules during a chain reorg.
• Technical Glitch: Nodes dropped restored parent transactions while retaining child descendants.
• Impact: Mempool corruption caused block template creation to fail validity checks.

Who Was Impacted and How Was It Resolved?

Miners and mining pool operators running vulnerable software versions faced the main risk.

Once the mempool became corrupted, template creation failed its validity checks.

As a result, the affected node stopped generating new block templates entirely.

Surprisingly, the fast fix was standard IT troubleshooting: restarting the node.

A restart forced the node to clear its corrupted mempool and rebuild it clean from scratch.

Disclosure Timeline and Responsible Security

Security researcher Niklas Goegge responsibly reported the flaw on September 26, 2025.

Developer Greg Sanders submitted the code fix shortly after.

Bitcoin Core released patched versions in October 2025, including versions 30.0, 29.2, and 28.3.

Why did developers wait until late 2026 to reveal public details?

Developers routinely delay full technical disclosures until older versions reach end-of-life.

This practice protects the network by giving node operators ample time to update.

Additional Bug Fixes and AI Security Tools

The November disclosure covered two other flaws addressed in version 30.0.

One flaw could stall block processing, while another granted incorrect permissions to inbound Tor connections.

This announcement followed an October batch of three bugs discovered by an AI scanner called Project Loupe.

Global Bitcoin Node Distribution and Recommendations

Bitcoin relies on a globally distributed network of nodes to remain secure.

According to data from Newhedge, the United States leads node distribution with 32.63%, followed by Germany and France.

Because node software is decentralized across many regions, keeping software up to date is essential.

Operators still using Bitcoin Core versions 28.0 through 29.1 should upgrade immediately.

If an unpatched node experiences mempool corruption, restarting it will clear bad transactions instantly.