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.
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History
Fri, 06 Nov 2026 22:00:00 +0000
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Wed, 04 Nov 2026 19:15:00 +0000
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| 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. | |
| Title | bitcoinjs-lib: Undetected merkle node duplication in block root computation validates a forged transaction list | |
| Weaknesses | CWE-354 | |
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cvssV4_0
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Status: PUBLISHED
Assigner: GitHub_M
Published: 2026-11-04T19:02:39.453Z
Updated: 2026-11-04T19:02:39.453Z
Reserved: 2026-10-08T22:34:49.291Z
Link: CVE-2026-107846
No data.
Status : Received
Published: 2026-11-04T19:17:18.130
Modified: 2026-11-04T19:17:18.130
Link: CVE-2026-107846
No data.
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