MEDIUM CVSS 6.4
Published: 2026-06-30

CVE-2026-10653

zephyrproject zephyr Security Advisory (CVE-2026-10653)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-10653 impacting zephyrproject zephyr. Evaluated with CVSS Base Score of 6.4 (MEDIUM).

Original NVD Description

Source: NIST NVD
The Zephyr net_buf library (lib/net_buf/buf.c) manipulated both of its reference counts -- the per-header buf->ref and the per-data-block ref_count at the start of each variable/heap data allocation -- with plain non-atomic C operators (buf->ref++, if (--buf->ref > 0), if (--(*ref_count))). The API is documented as self-synchronizing: callers may share one buffer across threads (e.g. via k_fifo) and each holder independently calls net_buf_unref() with no surrounding lock. Under true concurrency (SMP, or single-core preemption between the non-atomic load and store while another context unrefs the same buffer), two holders can both observe the same prior reference value and both conclude they are the last reference. For heap/variable-data pools (mem_pool_data_unref/heap_data_unref, used by zbus message subscribers, the IP stack RX/TX buffers when CONFIG_NET_BUF_FIXED_DATA_SIZE=n, capture, wireguard, ISO-TP and usbip) this produces a double k_heap_free()/k_free() of the same block -- heap-metadata corruption and a use-after-free on the heap-hardening poison pattern. For the per-header refcount the buffer is returned to the pool free LIFO twice for any pool type (including fixed-data pools used by Bluetooth and networking), corrupting the free list so a later allocation hands the same buffer to two owners. The fix converts both refcounts to atomic_inc/atomic_dec (overlaying buf->ref in an atomic_t-sized union and changing the data-block refcount from uint8_t to atomic_t). Impact is gated on genuine concurrency and on an application architecture that shares one buffer among multiple independent unref'ers; the trigger is a refcount/timing race rather than packet content, so an external attacker has at most weak indirect influence over the race window. Affects all Zephyr releases through v4.4.0.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Adjacent (AV:A)
Requires shared subnet / local network access
Attack Complexity
High (AC:H)
Depends on race conditions or environment
Privileges Required
None (PR:N)
Unauthenticated execution
User Interaction
None (UI:N)
Zero human interaction required
Scope
Unchanged (S:U)
Confined to same security context
Confidentiality
Low (C:L)
Partial information leakage
Integrity
Low (I:L)
Partial data modification possible
Availability
High (A:H)
Total denial of service or shutdown

🎯 Affected Versions Matrix

Affected Product zephyrproject / zephyr
Affected Versions *
Weakness Enumeration CWE-415

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-2026-10653 impacting zephyrproject zephyr.

⚡ Nuclei Detection Template (YAML) cve-2026-10653.yaml
id: cve-2026-10653

info:
  name: zephyrproject zephyr - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2026-10653 affecting zephyrproject zephyr.
    Evaluation: The Zephyr net_buf library (lib/net_buf/buf.c) manipulated both of its reference counts -- the per-header buf->ref and the per-data-block ref_count...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-10653
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
    cvss-score: 6.4
    cve-id: CVE-2026-10653
    cwe-id: CWE-415
  tags: cve,cve-2026-10653,zephyrproject,zephyr,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "zephyr"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-10653.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-10653
# Target: zephyrproject zephyr | CVSS: 6.4 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-10653 (zephyrproject zephyr)...")
    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 zephyrproject zephyr 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-2026-10653.sh
# Recommended Remediation & Patching Commands for CVE-2026-10653
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install zephyr 2>/dev/null || \
sudo dnf upgrade zephyr 2>/dev/null || \
sudo yum update zephyr

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

# 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.

🔗 Verified Technical References

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-10653 in zephyrproject zephyr?

Review vendor-specific security notices and update zephyrproject zephyr 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-2026-10653?

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-2026-10653?

CVE-2026-10653 is classified with a CVSS 3.1 Base Score of 6.4 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
6.4
MEDIUM SEVERITY
CVE ID CVE-2026-10653
Weakness CWE-415
Vendor zephyrproject
Product zephyr
Published 2026-06-30
Vector CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H