CVE-2026-46369: nimiq-blockchain Validity Store Off By One Vulnerability

HIGH
Advisory Identifier: GHSA-3763-qp59-59vf
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CVSS 7.5
CWE-294 CWE-193
Published
Advisory Summary

CVE-2026-46369 is a HIGH (CVSS 7.5) validity store off by one vulnerability (CWE-294: Authentication Bypass by Capture-replay) affecting nimiq-blockchain libraries in the crates.io ecosystem. The issue involves validity store off by one error. Remediation is available by upgrading affected packages to version 1.5.1.

CVE-2026-46369 at a Glance

CVE Identifier CVE-2026-46369
GHSA Identifier GHSA-3763-qp59-59vf
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-294: Authentication Bypass by Capture-replay
Affected Product nimiq-blockchain
Package Ecosystem crates.io
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity High (I:H)
Availability None (A:N)

How to Fix CVE-2026-46369

To remediate this vulnerability, upgrade all affected nimiq-blockchain dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

nimiq-blockchain fixed: 1.5.1 
Upgrade nimiq-blockchain to 1.5.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for nimiq-blockchain

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-46369, inspect your project dependencies for nimiq-blockchain:

inspect dependencies for nimiq-blockchain

Analyze the terminal output to locate any version of nimiq-blockchain in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.5.1), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-294: Authentication Bypass by Capture-replay, where a capture-replay flaw exists when the design of the product makes it possible for a malicious user to sniff network traffic and bypass authentication by replaying it to the server in question to the same effect as the original message (or with minor changes). In nimiq-blockchain, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact The validity store treats a transaction with stored `block_number = X` as "in window" only when `X > last_bn - transaction_validity_window_blocks` (strict inequality). However the protocol's `Transaction::is_valid_at` accepts a transaction for inclusion in any block in `[validity_start_height - blocks_per_batch, validity_start_height + window - 1]`. By choosing `validity_start_height = X + blocks_per_batch` (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 < validity_start_height + window`, i.e., a contiguous window of `blocks_per_batch - 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

CVE-2026-46369 Affected nimiq-blockchain Versions

1 component(s)
Fixed Versions:
1.5.1
Product / Package Ecosystem Affected Versions Fixed Version
nimiq-blockchain
 crates.io
< 1.5.1
1.5.1

References

GitHub Advisory / Wiki ADVISORY
https://github.com/nimiq/core-rs-albatross/security/advisories/GHSA-3763-qp59-59vf
nimiq-blockchain Source Repository REPOSITORY
https://github.com/nimiq/core-rs-albatross/pull/3772
Security Fix Commit FIX COMMIT
https://github.com/nimiq/core-rs-albatross/commit/a530b2434ebca6e3716f07c73079786fcc6f2e41
nimiq-blockchain Source Repository REPOSITORY
https://github.com/nimiq/core-rs-albatross

Frequently Asked Questions

What is CVE-2026-46369?
CVE-2026-46369 is a security vulnerability in nimiq-blockchain involving Validity store off by one error under CWE-294: Authentication Bypass by Capture-replay.
Which nimiq-blockchain versions are affected?
Affected versions include releases prior to 1.5.1 across affected packages: nimiq-blockchain.
What version fixes CVE-2026-46369?
Upgrading to 1.5.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is nimiq-blockchain affected?
Yes, nimiq-blockchain is affected in releases prior to 1.5.1. Upgrade your dependency to 1.5.1 or later.
What is the CVSS score of CVE-2026-46369?
CVE-2026-46369 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.
What CWE is associated with CVE-2026-46369?
CVE-2026-46369 is classified under CWE-294: Authentication Bypass by Capture-replay (A capture-replay flaw exists when the design of the product makes it possible for a malicious user to sniff network traffic and bypass authentication by replaying it to the server in question to the same effect as the original message (or with minor changes).).
How can I check crates.io dependencies for CVE-2026-46369?
Run the dependency tree command: 'inspect dependencies for nimiq-blockchain'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-3763-qp59-59vf",
  "modified" : "2026-08-12T15:16:53Z",
  "published" : "2026-08-12T15:16:53Z",
  "aliases" : [ "CVE-2026-46369" ],
  "summary" : "nimiq-blockchain: Validity store off by one error",
  "details" : "### Impact\nThe validity store treats a transaction with stored `block_number = X` as \"in window\" only when `X > last_bn - transaction_validity_window_blocks` (strict inequality). However the protocol's `Transaction::is_valid_at` accepts a transaction for inclusion in any block in `[validity_start_height - blocks_per_batch, validity_start_height + window - 1]`. By choosing `validity_start_height = X + blocks_per_batch` (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 < validity_start_height + window`, i.e., a contiguous window of `blocks_per_batch - 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.\n\n### Patches\nhttps://github.com/nimiq/core-rs-albatross/pull/3772\n\n### Workarounds\nNo known workarounds",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "nimiq-blockchain"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.5.1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.5.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/nimiq/core-rs-albatross/security/advisories/GHSA-3763-qp59-59vf"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/nimiq/core-rs-albatross/pull/3772"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/nimiq/core-rs-albatross/commit/a530b2434ebca6e3716f07c73079786fcc6f2e41"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/nimiq/core-rs-albatross"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-193", "CWE-294" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-12T15:16:53Z",
    "nvd_published_at" : null
  }
}