nimiq-blockchain: Validity store off by one error

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS

• CVE-2026-46369: 0.55% estimated exploitation activity in the next 30 days; percentile 46.00 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact The validity store treats a transaction with stored blocknumber = X as "in window" only when X lastbn - transactionvaliditywindowblocks (strict inequality). However the protocol's Transaction::isvalidat accepts a transaction for inclusion in any block in [validitystartheight - blocksperbatch, validitystartheight + window - 1]. By choosing validitystartheight = X + blocksperbatch (the largest value still compatible with first inclusion at block X), an attacker can replay the same signed transaction in any block B such that X + window < B < validitystartheight + window, i.e., a contiguous window of blocksperbatch - 1 blocks (59 on MainNet, ~10 minutes) during which the replay-protection check fails to flag it. The same transaction is then executed twice: the sender is debited twice, the recipient credited twice. Patches https://github.com/nimiq/core-rs-albatross/pull/3772 Workarounds No known workarounds

Published by the source

12 Aug 2026, 15:16 UTC

Last modified by the source

4 Oct 2026, 22:11 UTC

Source last checked

26 Oct 2026, 15:43 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-3763-qp59-59vf

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-3763-qp59-59vf

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# Patch Next advisory brief: CVE-2026-46369

Advisory: nimiq-blockchain: Validity store off by one error
IDs: CVE-2026-46369, GHSA-3763-qp59-59vf
Record: https://patchnext.com/advisories/cve-2026-46369 (revision 2, source checked 26 Oct 2026, 15:43 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: nimiq-blockchain 1.5.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io nimiq-blockchain: affected <= 1.5.0; fixed in 1.5.1

## Suggested inspection (read-only)
- crates.io nimiq-blockchain: check the installed version with your package manager.

## 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 nimiq-blockchain.
- 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://osv.dev/vulnerability/GHSA-3763-qp59-59vf (OSV record GHSA-3763-qp59-59vf lists affected ranges: crates.io nimiq-blockchain >=0 <1.5.1 (fixed))
- Verified: https://github.com/advisories/GHSA-3763-qp59-59vf (GitHub-reviewed advisory GHSA-3763-qp59-59vf lists affected ranges: crates.io nimiq-blockchain >=0 <=1.5.0)

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