HIGH CVSS 7.8
Published: 2026-06-26

CVE-2026-45257

freebsd freebsd Security Advisory (CVE-2026-45257)
↗ Official NIST NVD Record
Seeking technical exploit breakdowns or verified PoC code for CVE-2026-45257?
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-45257 impacting freebsd freebsd. Evaluated with CVSS Base Score of 7.8 (HIGH).

Original NVD Description

Source: NIST NVD
The KTLS receive path decrypted each record in place, assuming that the mbufs holding received data were anonymous and safe to modify. This assumption does not hold for data placed on a socket by sendfile(2), which can reference file-backed memory directly through non-anonymous M_EXTPG pages or EXT_SFBUF mbufs. When the sender transmits such data over a loopback connection without enabling KTLS on the transmit side, the file-backed mbufs reach the receiver's decryption path unchanged. Decrypting a record in place then overwrites the backing file's page cache instead of a private copy of the data. An unprivileged local user who can read a file can overwrite its contents with data of their choosing by sending the file over a loopback connection on which they have enabled KTLS receive. The write modifies the page cache directly, so it bypasses file flags such as schg and is written back to disk. By overwriting a setuid binary or other trusted file, a local user can escalate privileges, potentially gaining full control of the affected system.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Local (AV:L)
Requires local system execution permissions
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
High (I:H)
Total modification of target system
Availability
High (A:H)
Total denial of service or shutdown

🎯 Affected Versions Matrix

Affected Product freebsd / freebsd
Affected Versions 14.3
Weakness Enumeration CWE-123

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-2026-45257 impacting freebsd freebsd.

⚡ Nuclei Detection Template (YAML) cve-2026-45257.yaml
id: cve-2026-45257

info:
  name: freebsd freebsd - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: high
  description: |
    Automated signature & scanner for CVE-2026-45257 affecting freebsd freebsd.
    Evaluation: The KTLS receive path decrypted each record in place, assuming that the mbufs holding received data were anonymous and safe to modify.  This assumptio...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-45257
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 7.8
    cve-id: CVE-2026-45257
    cwe-id: CWE-123
  tags: cve,cve-2026-45257,freebsd,freebsd,high

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "freebsd"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-45257.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-45257
# Target: freebsd freebsd | CVSS: 7.8 (HIGH)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-45257 (freebsd freebsd)...")
    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 freebsd freebsd scope (14.3).")
        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-2026-45257.sh
# Recommended Remediation & Patching Commands for CVE-2026-45257
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install freebsd 2>/dev/null || \
sudo dnf upgrade freebsd 2>/dev/null || \
sudo yum update freebsd

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

# 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-2026-45257 in freebsd freebsd?

Review vendor-specific security notices and update freebsd freebsd 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-2026-45257?

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-2026-45257?

CVE-2026-45257 is classified with a CVSS 3.1 Base Score of 7.8 (HIGH). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
7.8
HIGH SEVERITY
CVE ID CVE-2026-45257
Weakness CWE-123
Vendor freebsd
Product freebsd
Published 2026-06-26
Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H