MEDIUM CVSS 4.1
Published: 2026-07-01

CVE-2026-13323

eclipse open_vsx Security Advisory (CVE-2026-13323)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-13323 impacting eclipse open_vsx. Evaluated with CVSS Base Score of 4.1 (MEDIUM).

Original NVD Description

Source: NIST NVD
In Open VSX Registry before 1.0.2, the /vscode/unpkg/ endpoint serves user-supplied HTML files with Content-Type: text/html and without a Content-Security-Policy or Content-Disposition: attachment response header. An unauthenticated attacker can register a publisher account, upload a VSIX containing a crafted HTML payload, and induce an authenticated user to visit the resulting URL. The browser renders the file inline in the open-vsx.org origin context, enabling session token exfiltration, persistent Personal Access Token (PAT) generation, and unauthorized publication of malicious extension versions. Because Open VSX extensions are distributed to VS Code, VSCodium, Cursor, Windsurf, and compatible editors, a compromised extension update constitutes a supply chain attack against all downstream users.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Network (AV:N)
Exploitable remotely across internet boundaries
Attack Complexity
Low (AC:L)
No specialized conditions required
Privileges Required
Low (PR:L)
Standard user access required
User Interaction
Required (UI:R)
User must click or open resource
Scope
Changed (S:C)
Impacts components beyond caller authority
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 eclipse / open_vsx
Affected Versions *
Weakness Enumeration CWE-79

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-2026-13323 impacting eclipse open_vsx.

⚡ Nuclei Detection Template (YAML) cve-2026-13323.yaml
id: cve-2026-13323

info:
  name: eclipse open_vsx - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2026-13323 affecting eclipse open_vsx.
    Evaluation: In Open VSX Registry before 1.0.2, the /vscode/unpkg/ endpoint serves user-supplied HTML files with Content-Type: text/html and without a Content-Secu...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-13323
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N
    cvss-score: 4.1
    cve-id: CVE-2026-13323
    cwe-id: CWE-79
  tags: cve,cve-2026-13323,eclipse,open_vsx,medium

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "open_vsx"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-13323.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-13323
# Target: eclipse open_vsx | CVSS: 4.1 (MEDIUM)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-13323 (eclipse open_vsx)...")
    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 eclipse open_vsx 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-2026-13323.sh
# Recommended Remediation & Patching Commands for CVE-2026-13323
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install open_vsx 2>/dev/null || \
sudo dnf upgrade open_vsx 2>/dev/null || \
sudo yum update open_vsx

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

# 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-2026-13323 in eclipse open_vsx?

Review vendor-specific security notices and update eclipse open_vsx 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-2026-13323?

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-2026-13323?

CVE-2026-13323 is classified with a CVSS 3.1 Base Score of 4.1 (MEDIUM). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
4.1
MEDIUM SEVERITY
CVE ID CVE-2026-13323
Weakness CWE-79
Vendor eclipse
Product open_vsx
Published 2026-07-01
Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N