MEDIUM CVSS 5.5
Published: 2026-04-07

CVE-2026-5745

libarchive libarchive Security Advisory (CVE-2026-5745)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-5745 impacting libarchive libarchive. Evaluated with CVSS Base Score of 5.5 (MEDIUM).

Original NVD Description

Source: NIST NVD
A flaw was found in libarchive. A NULL pointer dereference vulnerability exists in the ACL parsing logic, specifically within the archive_acl_from_text_nl() function. When processing a malformed ACL string (such as a bare "d" or "default" tag without subsequent fields), the function fails to perform adequate validation before advancing the pointer. An attacker can exploit this by providing a maliciously crafted archive, causing an application utilizing the libarchive API (such as bsdtar) to crash, resulting in a Denial of Service (DoS).

📊 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
None (PR:N)
Unauthenticated execution
User Interaction
Required (UI:R)
User must click or open resource
Scope
Unchanged (S:U)
Confined to same security context
Confidentiality
None (C:N)
No data confidentiality impact
Integrity
None (I:N)
No system modification impact
Availability
High (A:H)
Total denial of service or shutdown

🎯 Affected Versions Matrix

Affected Product libarchive / libarchive
Affected Versions -
Weakness Enumeration CWE-476

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-2026-5745 impacting libarchive libarchive.

⚡ Nuclei Detection Template (YAML) cve-2026-5745.yaml
id: cve-2026-5745

info:
  name: libarchive libarchive - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2026-5745 affecting libarchive libarchive.
    Evaluation: A flaw was found in libarchive. A NULL pointer dereference vulnerability exists in the ACL parsing logic, specifically within the archive_acl_from_tex...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-5745
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
    cvss-score: 5.5
    cve-id: CVE-2026-5745
    cwe-id: CWE-476
  tags: cve,cve-2026-5745,libarchive,libarchive,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "libarchive"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-5745.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-5745
# Target: libarchive libarchive | CVSS: 5.5 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-5745 (libarchive libarchive)...")
    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 libarchive libarchive 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-2026-5745.sh
# Recommended Remediation & Patching Commands for CVE-2026-5745
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install libarchive 2>/dev/null || \
sudo dnf upgrade libarchive 2>/dev/null || \
sudo yum update libarchive

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

# 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

Authorities
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Technical Analysis
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❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-5745 in libarchive libarchive?

Review vendor-specific security notices and update libarchive libarchive 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-2026-5745?

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-2026-5745?

CVE-2026-5745 is classified with a CVSS 3.1 Base Score of 5.5 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
5.5
MEDIUM SEVERITY
CVE ID CVE-2026-5745
Weakness CWE-476
Vendor libarchive
Product libarchive
Published 2026-04-07
Vector CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H