CVE-2026-107846

CRITICAL

INFO Priority: 0.02 BB Relevance: 79/100

Published: 2026-11-04 Modified: 2026-11-04 First seen: 2026-11-04 Status: active

Attack Surface

Network Low Complexity No Auth No Interaction Integ. Impact

CVSS Vector Breakdown

AV: Network

AC: Low

PR: None

UI: None

AT: None

VC: Low

VI: High

VA: Low

Description

bitcoinjs-lib is a JavaScript Bitcoin library for Node.js and browsers. From 2.3.0 until 5.2.1, 6.1.8, and 7.0.2, fastMerkleRoot pads odd Merkle-tree levels by hashing the final node with itself but does not report adjacent duplicate hashes. The affected block-root verifier was introduced as Block.checkMerkleRoot() alongside Block.calculateMerkleRoot(), while later versions expose validation through checkTxRoots() and __checkMerkleRoot; these validation paths can accept a recomputed root without checking for mutation. A peer can append duplicate transactions so a different transaction list retains the original Merkle root, block header, proof of work, and block identifier. Consumers that rely on block-root validation, including explorers, exchange indexers, or SPV clients, can process a duplicated transaction twice or blacklist the shared block hash and reject the honest block. This issue is fixed in versions 5.2.1, 6.1.8, and 7.0.2.