HIGH CVSS 8.1
Published: 2026-02-13

CVE-2026-26264

bacnetstack bacnet_stack Security Advisory (CVE-2026-26264)
โ†— Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-26264 impacting bacnetstack bacnet_stack. Evaluated with CVSS Base Score of 8.1 (HIGH).

Original NVD Description

Source: NIST NVD
BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.5.0rc4 and 1.4.3rc2, a malformed WriteProperty request can trigger a length underflow in the BACnet stack, leading to an outโ€‘ofโ€‘bounds read and a crash (DoS). The issue is in wp.c within wp_decode_service_request. When decoding the optional priority context tag, the code passes apdu_len - apdu_size to bacnet_unsigned_context_decode without validating that apdu_size <= apdu_len. If a truncated APDU reaches this path, apdu_len - apdu_size underflows, resulting in a large size being used for decoding and an outโ€‘ofโ€‘bounds read. This vulnerability is fixed in 1.5.0rc4 and 1.4.3rc2.

๐Ÿ“Š 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
Unchanged (S:U)
Confined to same security context
Confidentiality
High (C:H)
Total information disclosure
Integrity
None (I:N)
No system modification impact
Availability
High (A:H)
Total denial of service or shutdown

๐ŸŽฏ Affected Versions Matrix

Affected Product bacnetstack / bacnet_stack
Affected Versions *
Weakness Enumeration CWE-125

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-2026-26264 impacting bacnetstack bacnet_stack.

โšก Nuclei Detection Template (YAML) cve-2026-26264.yaml
id: cve-2026-26264

info:
  name: bacnetstack bacnet_stack - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: high
  description: |
    Automated signature & scanner for CVE-2026-26264 affecting bacnetstack bacnet_stack.
    Evaluation: BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.5.0rc4 and 1.4.3rc2, a malformed WriteProperty request ...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-26264
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
    cvss-score: 8.1
    cve-id: CVE-2026-26264
    cwe-id: CWE-125
  tags: cve,cve-2026-26264,bacnetstack,bacnet_stack,high

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "bacnet_stack"
        part: body
๐Ÿ PoC Exploit & Verification Probe (Python 3) poc_cve-2026-26264.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-26264
# Target: bacnetstack bacnet_stack | CVSS: 8.1 (HIGH)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-26264 (bacnetstack bacnet_stack)...")
    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 bacnetstack bacnet_stack 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)
๐Ÿ›ก๏ธ Quick Patch & Remediation Script (Bash) patch_cve-2026-26264.sh
# Recommended Remediation & Patching Commands for CVE-2026-26264
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install bacnet_stack 2>/dev/null || \
sudo dnf upgrade bacnet_stack 2>/dev/null || \
sudo yum update bacnet_stack

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

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

๐Ÿ›ก๏ธ 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.
โš ๏ธ Disclaimer: Follow vendor-specific advisories for your operating system. CyberVault does not fabricate unsupported remediation scripts.

๐Ÿ”— Verified Technical References

โ“ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-26264 in bacnetstack bacnet_stack?

Review vendor-specific security notices and update bacnetstack bacnet_stack 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-2026-26264?

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-2026-26264?

CVE-2026-26264 is classified with a CVSS 3.1 Base Score of 8.1 (HIGH). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
8.1
HIGH SEVERITY
CVE ID CVE-2026-26264
Weakness CWE-125
Vendor bacnetstack
Product bacnet_stack
Published 2026-02-13
Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H