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Critical, CVSS 9.3amended

bitcoinjs-lib: Undetected merkle node duplication in block root computation validates a forged transaction list

CVE-2026-107846GHSA-8vv3-6qpc-gpw6

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (bitcoinjs-lib 7.0.2, 6.1.8, 5.2.1), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • npm bitcoinjs-lib

    Affected
    >= 2.3.0, < 5.2.1>= 6.0.0, < 6.1.8>= 7.0.0-rc.0, < 7.0.2
    Fixed in
    5.2.1, 6.1.8, 7.0.2

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
9.3 · 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 · score source
EPSS
  • CVE-2026-107846: 0.18% estimated exploitation activity in the next 30 days; percentile 7.59 (FIRST EPSS, 2026-11-10). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary fastMerkleRoot pads an odd level by hashing the last node with itself. It does not report that it did so, and checkTxRoots never looks for repeated transactions. A peer can therefore duplicate transactions to fill the pad and produce a block with a different transaction list but the same merkle root. The block hash and block id do not change, so the header still carries valid proof of work. In the proof of concept a real mainnet block goes from nine transactions to ten, and separately to twelve, with the same id every time, and checkTxRoots accepts all three. Bitcoin Core rejects this case through the mutated flag in ComputeMerkleRoot and the bad-txns-duplicate reason in CheckBlock. This is CVE-2012-2459. Details A bitcoin merkle tree pads an odd level by hashing the last node with itself. Duplicating transactions to fill that pad therefore yields the same root for a different transaction list. This is CVE-2012-2459. Bitcoin Core detects it in ComputeMerkleRoot, which scans…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-8vv3-6qpc-gpw6

  2. Revision 2 · amended ·

    Amended from osv record GHSA-8vv3-6qpc-gpw6

  3. Revision 1 · created ·

    Published from ghsa record GHSA-8vv3-6qpc-gpw6

Agent brief

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# Patch Next advisory brief: CVE-2026-107846

Advisory: bitcoinjs-lib: Undetected merkle node duplication in block root computation validates a forged transaction list
IDs: CVE-2026-107846, GHSA-8vv3-6qpc-gpw6
Record: https://patchnext.com/advisories/cve-2026-107846 (revision 3, source checked 11 Nov 2026, 06:05 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: bitcoinjs-lib 7.0.2, 6.1.8, 5.2.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm bitcoinjs-lib: affected >= 2.3.0, < 5.2.1; >= 6.0.0, < 6.1.8; >= 7.0.0-rc.0, < 7.0.2; fixed in 5.2.1, 6.1.8, 7.0.2

## Suggested inspection (read-only)
- `npm ls bitcoinjs-lib --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on bitcoinjs-lib.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-8vv3-6qpc-gpw6 (GitHub-reviewed advisory GHSA-8vv3-6qpc-gpw6 lists affected ranges: npm bitcoinjs-lib >=2.3.0 =6.0.0 =7.0.0-rc.0 <7.0.2)
- Verified: https://osv.dev/vulnerability/GHSA-8vv3-6qpc-gpw6 (OSV record GHSA-8vv3-6qpc-gpw6 lists affected ranges: npm bitcoinjs-lib >=2.3.0 =6.0.0 =7.0.0-rc.0 <7.0.2 (fixed))

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