LOW CVSS 2.0
Published: 2026-02-06

CVE-2026-23739

sangoma asterisk Security Advisory (CVE-2026-23739)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-23739 impacting sangoma asterisk. Evaluated with CVSS Base Score of 2.0 (LOW).

Original NVD Description

Source: NIST NVD
Asterisk is an open source private branch exchange and telephony toolkit. Prior to versions 20.7-cert9, 20.18.2, 21.12.1, 22.8.2, and 23.2.2, the ast_xml_open() function in xml.c parses XML documents using libxml with unsafe parsing options that enable entity expansion and XInclude processing. Specifically, it invokes xmlReadFile() with the XML_PARSE_NOENT flag and later processes XIncludes via xmlXIncludeProcess().If any untrusted or user-supplied XML file is passed to this function, it can allow an attacker to trigger XML External Entity (XXE) or XInclude-based local file disclosure, potentially exposing sensitive files from the host system. This can also be triggered in other cases in which the user is able to supply input in xml format that triggers the asterisk process to parse it. This issue has been patched in versions 20.7-cert9, 20.18.2, 21.12.1, 22.8.2, and 23.2.2.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Network (AV:N)
Exploitable remotely across internet boundaries
Attack Complexity
High (AC:H)
Depends on race conditions or environment
Privileges Required
High (PR:H)
Administrative credentials required
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
Low (I:L)
Partial data modification possible
Availability
None (A:N)
No system availability impact

🎯 Affected Versions Matrix

Affected Product sangoma / asterisk
Affected Versions *
Weakness Enumeration CWE-611

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-2026-23739 impacting sangoma asterisk.

⚡ Nuclei Detection Template (YAML) cve-2026-23739.yaml
id: cve-2026-23739

info:
  name: sangoma asterisk - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: low
  description: |
    Automated signature & scanner for CVE-2026-23739 affecting sangoma asterisk.
    Evaluation: Asterisk is an open source private branch exchange and telephony toolkit. Prior to versions 20.7-cert9, 20.18.2, 21.12.1, 22.8.2, and 23.2.2, the ast_...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-23739
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:L/A:N
    cvss-score: 2.0
    cve-id: CVE-2026-23739
    cwe-id: CWE-611
  tags: cve,cve-2026-23739,sangoma,asterisk,low

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "asterisk"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-23739.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-23739
# Target: sangoma asterisk | CVSS: 2.0 (LOW)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-23739 (sangoma asterisk)...")
    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 sangoma asterisk 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-2026-23739.sh
# Recommended Remediation & Patching Commands for CVE-2026-23739
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install asterisk 2>/dev/null || \
sudo dnf upgrade asterisk 2>/dev/null || \
sudo yum update asterisk

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

# 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
  • No records filed in this category.
Distributions
  • No records filed in this category.

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-23739 in sangoma asterisk?

Review vendor-specific security notices and update sangoma asterisk 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-2026-23739?

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-2026-23739?

CVE-2026-23739 is classified with a CVSS 3.1 Base Score of 2.0 (LOW). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
2.0
LOW SEVERITY
CVE ID CVE-2026-23739
Weakness CWE-611
Vendor sangoma
Product asterisk
Published 2026-02-06
Vector CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:L/A:N