{"id":"CVE-2026-107846","title":"bitcoinjs-lib: Undetected merkle node duplication in block root computation validates a forged transaction list","summary":"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 has…","severity":"critical","cvss":9.3,"cvssVector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:L/SC:N/SI:H/SA:H","cvssSource":"cna","cwe":["CWE-354"],"vendor":"bitcoinjs","product":"bitcoinjs-lib","affected":["bitcoinjs-lib >= 2.3.0, < 5.2.1","bitcoinjs-lib >= 6.0.0, < 6.1.8","bitcoinjs-lib >= 7.0.0-rc.0, < 7.0.2"],"published":"2026-11-04","updated":"2026-11-04","sourceUpdated":"2026-11-04T19:02:39.453Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-107846","references":[{"url":"https://github.com/bitcoinjs/bitcoinjs-lib/security/advisories/GHSA-8vv3-6qpc-gpw6","label":"https://github.com/bitcoinjs/bitcoinjs-lib/security/advisories/GHSA-8vv3-6qpc-gpw6"},{"url":"https://github.com/bitcoinjs/bitcoinjs-lib/commit/009f165edfbf925cad8964b2dce478d18dd19449","label":"https://github.com/bitcoinjs/bitcoinjs-lib/commit/009f165edfbf925cad8964b2dce478d18dd19449"},{"url":"https://github.com/bitcoinjs/bitcoinjs-lib/commit/b79c7714c0687473dc6e25c69fc5fc597302c7a0","label":"https://github.com/bitcoinjs/bitcoinjs-lib/commit/b79c7714c0687473dc6e25c69fc5fc597302c7a0"},{"url":"https://github.com/bitcoinjs/bitcoinjs-lib/commit/f3434d1e4bb5e0784fe769c4cd08a243576232a1","label":"https://github.com/bitcoinjs/bitcoinjs-lib/commit/f3434d1e4bb5e0784fe769c4cd08a243576232a1"}],"tags":["cve.org"],"ingestedAt":"2026-11-05T21:36:00.517Z","epss":0.0018,"epssPercentile":0.07573,"slug":"CVE-2026-107846","body":"## Overview\n\nbitcoinjs-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.\n\n## Affected\n\n- `bitcoinjs-lib >= 2.3.0, < 5.2.1`\n- `bitcoinjs-lib >= 6.0.0, < 6.1.8`\n- `bitcoinjs-lib >= 7.0.0-rc.0, < 7.0.2`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"midnight","depthScore":51,"depthScoreParts":{"impact":51.2,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}