HIGH CVSS 7.0
Published: 2026-05-20

CVE-2026-29518

samba rsync Security Advisory (CVE-2026-29518)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-29518 impacting samba rsync. Evaluated with CVSS Base Score of 7.0 (HIGH).

Original NVD Description

Source: NIST NVD
Rsync versions before 3.4.3 contain a time-of-check to time-of-use (TOCTOU) race condition in daemon file handling that allows attackers to redirect file writes outside intended directories by replacing parent directory components with symbolic links. Attackers with write access to a module path can exploit this race condition to create or overwrite arbitrary files, potentially modifying sensitive system files and achieving privilege escalation when the daemon runs with elevated privileges. This vulnerability can only be triggered if the chroot setting is false.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Local (AV:L)
Requires local system execution permissions
Attack Complexity
High (AC:H)
Depends on race conditions or environment
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
High (I:H)
Total modification of target system
Availability
High (A:H)
Total denial of service or shutdown

🎯 Affected Versions Matrix

Affected Product samba / rsync
Affected Versions *
Weakness Enumeration CWE-367

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-2026-29518 impacting samba rsync.

⚡ Nuclei Detection Template (YAML) cve-2026-29518.yaml
id: cve-2026-29518

info:
  name: samba rsync - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: high
  description: |
    Automated signature & scanner for CVE-2026-29518 affecting samba rsync.
    Evaluation: Rsync versions before 3.4.3 contain a time-of-check to time-of-use (TOCTOU) race condition in daemon file handling that allows attackers to redirect f...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-29518
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 7.0
    cve-id: CVE-2026-29518
    cwe-id: CWE-367
  tags: cve,cve-2026-29518,samba,rsync,high

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "rsync"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-29518.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-29518
# Target: samba rsync | CVSS: 7.0 (HIGH)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-29518 (samba rsync)...")
    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 samba rsync 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-2026-29518.sh
# Recommended Remediation & Patching Commands for CVE-2026-29518
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install rsync 2>/dev/null || \
sudo dnf upgrade rsync 2>/dev/null || \
sudo yum update rsync

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

# 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-2026-29518 in samba rsync?

Review vendor-specific security notices and update samba rsync 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-2026-29518?

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-2026-29518?

CVE-2026-29518 is classified with a CVSS 3.1 Base Score of 7.0 (HIGH). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
7.0
HIGH SEVERITY
CVE ID CVE-2026-29518
Weakness CWE-367
Vendor samba
Product rsync
Published 2026-05-20
Vector CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H