CVE-2025-24371

Date: February 3, 2025

CometBFT is a distributed, Byzantine fault-tolerant, deterministic state machine replication engine. In the "blocksync" protocol peers send their "base" and "latest" heights when they connect to a new node ("A"), which is syncing to the tip of a network. "base" acts as a lower ground and informs "A" that the peer only has blocks starting from height "base". "latest" height informs "A" about the latest block in a network. Normally, nodes would only report increasing heights. If "B" fails to provide the latest block, "B" is removed and the "latest" height (target height) is recalculated based on other nodes "latest" heights. The existing code however doesn't check for the case where "B" first reports "latest" height "X" and immediately after height "Y", where "X > Y". "A" will be trying to catch up to 2000 indefinitely. This condition requires the introduction of malicious code in the full node first reporting some non-existing "latest" height, then reporting lower "latest" height and nodes which are syncing using "blocksync" protocol. This issue has been patched in versions 1.0.1 and 0.38.17 and all users are advised to upgrade. Operators may attempt to ban malicious peers from the network as a workaround.