Bitcoin Core bug lets malicious peers crash Windows and Mac nodes

A medium-severity flaw involving TCP urgent data could exhaust memory on non-Linux machines, and patched versions are already out Bitcoin Core has disclosed a bug that lets a malicious peer crash nodes running on Windows and macOS by flooding them into memory exhaustion. The fix is already available, which means the main remaining risk is the operator who never clicks update. The flaw was one of three vulnerabilities disclosed on October 28, 2026. It carries a medium-severity rating and affects nodes on non-Linux operating systems. How the crash works An attacker connected as a peer sends TCP urgent data, also called out-of-band data. This is a networking feature that lets a sender flag certain bytes for special handling. The problem sits in how software watches network connections. Bitcoin Core’s advisory points to differences between two socket monitoring mechanisms, select() and poll(). Those differences can be abused to cause unbounded memory growth on affected platforms. The node keeps setting memory aside and never stops. Eventually it runs out, and the software crashes. A crashed node is not stolen funds. It is, however, a node that has stopped doing its job of validating an...