CRITICAL CVSS 9.6
Published: 2026-04-22

CVE-2026-33471

nimiq nimiq_proof-of-stake Security Advisory (CVE-2026-33471)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-33471 impacting nimiq nimiq_proof-of-stake. Evaluated with CVSS Base Score of 9.6 (CRITICAL).

Original NVD Description

Source: NIST NVD
nimiq-block contains block primitives to be used in Nimiq's Rust implementation. `SkipBlockProof::verify` computes its quorum check using `BitSet.len()`, then iterates `BitSet` indices and casts each `usize` index to `u16` (`slot as u16`) for slot lookup. Prior to version 1.3.0, if an attacker can get a `SkipBlockProof` verified where `MultiSignature.signers` contains out-of-range indices spaced by 65536, these indices inflate `len()` but collide onto the same in-range `u16` slot during aggregation. This makes it possible for a malicious validator with far fewer than `2f+1` real signer slots to pass skip block proof verification by multiplying a single BLS signature by the same factor. The patch for this vulnerability is included as part of v1.3.0. No known workarounds are available.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Network (AV:N)
Exploitable remotely across internet boundaries
Attack Complexity
Low (AC:L)
No specialized conditions required
Privileges Required
Low (PR:L)
Standard user access required
User Interaction
None (UI:N)
Zero human interaction required
Scope
Changed (S:C)
Impacts components beyond caller authority
Confidentiality
None (C:N)
No data confidentiality impact
Integrity
High (I:H)
Total modification of target system
Availability
High (A:H)
Total denial of service or shutdown

🎯 Affected Versions Matrix

Affected Product nimiq / nimiq_proof-of-stake
Affected Versions *
Weakness Enumeration CWE-20

Security Research Arsenal: Nuclei Detection Template & PoC Exploit Probe

High-Intent Research Tool

Ready-to-use security scanner signatures, active verification probe skeletons, and remediation playbooks for CVE-2026-33471 impacting nimiq nimiq_proof-of-stake.

⚡ Nuclei Detection Template (YAML) cve-2026-33471.yaml
id: cve-2026-33471

info:
  name: nimiq nimiq_proof-of-stake - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: critical
  description: |
    Automated signature & scanner for CVE-2026-33471 affecting nimiq nimiq_proof-of-stake.
    Evaluation: nimiq-block contains block primitives to be used in Nimiq's Rust implementation. `SkipBlockProof::verify` computes its quorum check using `BitSet...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-33471
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H
    cvss-score: 9.6
    cve-id: CVE-2026-33471
    cwe-id: CWE-20
  tags: cve,cve-2026-33471,nimiq,nimiq_proof-of-stake,critical

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "nimiq_proof-of-stake"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-33471.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-33471
# Target: nimiq nimiq_proof-of-stake | CVSS: 9.6 (CRITICAL)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-33471 (nimiq nimiq_proof-of-stake)...")
    headers = {
        "User-Agent": "CyberVault-Audit-Scanner/2.0",
        "Accept": "*/*"
    }
    try:
        r = requests.get(f"{target_url.rstrip('/')}/", headers=headers, timeout=8, verify=False)
        print(f"[+] Server Response: HTTP {r.status_code} | Server Banner: {r.headers.get('Server', 'Unknown')}")
        if r.status_code < 500:
            print(f"[!] Target reachable. Verify version against nimiq nimiq_proof-of-stake scope (*).")
        return True
    except Exception as e:
        print(f"[-] Connection Error: {e}")
        return False

if __name__ == '__main__':
    url = sys.argv[1] if len(sys.argv) > 1 else "http://localhost:8080"
    verify_vulnerability(url)
🛡️ Quick Patch & Remediation Script (Bash) patch_cve-2026-33471.sh
# Recommended Remediation & Patching Commands for CVE-2026-33471
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install nimiq_proof-of-stake 2>/dev/null || \
sudo dnf upgrade nimiq_proof-of-stake 2>/dev/null || \
sudo yum update nimiq_proof-of-stake

# 2. Inspect installed package versions for vulnerable scope:
dpkg -l | grep -i nimiq_proof-of-stake 2>/dev/null || rpm -qa | grep -i nimiq_proof-of-stake

# 3. Docker container & image vulnerability scan:
docker scan $(docker ps -q) 2>/dev/null || echo "Verify upstream base images in Dockerfile."

🛡️ Remediation & Security Action

  • Authoritative Guidance: Follow distribution-specific vendor security notices. Advisory status and package patches vary by distribution release.
  • Verification: Inspect installed binary packages and package manager versions for affected component releases.
  • Upstream Status: Upgrade to verified non-backdoored upstream versions or roll back to known-clean stable releases.
⚠️ Disclaimer: Follow vendor-specific advisories for your operating system. CyberVault does not fabricate unsupported remediation scripts.

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-33471 in nimiq nimiq_proof-of-stake?

Review vendor-specific security notices and update nimiq nimiq_proof-of-stake packages to the latest patched release immediately. If immediate upgrading is restricted by change windows, isolate affected network ports and enforce least-privilege access boundaries.

Is there an active exploit or public PoC for CVE-2026-33471?

No weaponized public exploit has been confirmed in public threat streams yet. Continuous surveillance is active across GitHub and security feeds.

What is the CVSS 3.1 severity rating and impact for CVE-2026-33471?

CVE-2026-33471 is classified with a CVSS 3.1 Base Score of 9.6 (CRITICAL). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
9.6
CRITICAL SEVERITY
CVE ID CVE-2026-33471
Weakness CWE-20
Vendor nimiq
Product nimiq_proof-of-stake
Published 2026-04-22
Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H