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CVE-2026-107846VulnerabilityPublished

bitcoinjs-lib: Undetected merkle node duplication

Affects bitcoinjs-libSource GCVE Database

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Mentioned vulnerabilities

Authoritative record:CVE-2026-107846· Critical 9.3

Not known to be exploited · CVSS 9.3 Critical : upgrade to 5.2.1 as a priority.

Data as of 10 Nov 2026, 17:35 UTC

CVSS 4.0 base score
9.3Critical
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (GitHub_M)CVSS 4.09.3
Patch
Available – fixed in 5.2.1, 6.1.8, 7.0.2
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 4 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.

What to do

Upgrade bitcoinjs-lib to 5.2.1; bitcoinjs-lib to 6.1.8; bitcoinjs-lib to 7.0.2.

Affected software

ProductAffectedFixed in
npmbitcoinjs-libAffected
  • >=2.3.0 <5.2.1
Fixed in
  • 5.2.1
npmbitcoinjs-libAffected
  • >=6.0.0 <6.1.8
Fixed in
  • 6.1.8
npmbitcoinjs-libAffected
  • >=7.0.0-rc.0 <7.0.2
Fixed in
  • 7.0.2

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Fixed versions 5.2.1, 6.1.8, and 7.0.2 of bitcoinjs-lib address this vulnerability by presumably implementing checks to detect duplicated transactions in the Merkle tree computation. Users should upgrade to these versions or later. Since patchAvailable is true and fixedVersions are known, upgrading to these versions is the recommended remediation. No other mitigation is indicated by the vendor advisory.

Description

bitcoinjs-lib versions prior to 5.2.1, 6.1.8, and 7.0.2 contain a vulnerability (CVE-2026-107846) where the fastMerkleRoot function does not detect duplicated transactions used to pad odd levels in the Merkle tree. This allows a forged block with a different transaction list but the same Merkle root and block ID to be accepted by the library's checkTxRoots function. Bitcoin Core mitigates this by detecting such mutations and rejecting the block, but bitcoinjs-lib lacks this check.

References

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