MEDIUM CVSS 4.1
Published: 2026-06-23

CVE-2026-4983

eclipse open_vsx Security Advisory (CVE-2026-4983)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-4983 impacting eclipse open_vsx. Evaluated with CVSS Base Score of 4.1 (MEDIUM).

Original NVD Description

Source: NIST NVD
Open VSX Registry does not sanitize SVG files uploaded as extension icons prior to storage, and serves them with Content-Type: image/svg+xml without security headers such as Content-Security-Policy or Content-Disposition: attachment. This allows an attacker to publish an extension with a malicious SVG icon and achieve stored cross-site scripting (XSS) when a user navigates directly to the icon URL. On deployments using local storage, script execution occurs within the Open VSX application origin, enabling session hijacking, authentication token theft, and unauthorized extension publishing. On deployments backed by external storage (such as open-vsx.org with an S3-backed CDN), execution is confined to the storage origin, reducing impact but still permitting phishing attacks and credential harvesting through attacker-crafted pages.

📊 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-2026-4983 impacting eclipse open_vsx.

⚡ Nuclei Detection Template (YAML) cve-2026-4983.yaml
id: cve-2026-4983

info:
  name: eclipse open_vsx - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: medium
  description: |
    Automated signature & scanner for CVE-2026-4983 affecting eclipse open_vsx.
    Evaluation: Open VSX Registry does not sanitize SVG files uploaded as extension icons prior to storage, and serves them with Content-Type: image/svg+xml without s...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-4983
  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-2026-4983
    cwe-id: CWE-79
  tags: cve,cve-2026-4983,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-2026-4983.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-4983
# 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-2026-4983 (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-2026-4983.sh
# Recommended Remediation & Patching Commands for CVE-2026-4983
# 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

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-2026-4983 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-2026-4983?

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-2026-4983?

CVE-2026-4983 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-2026-4983
Weakness CWE-79
Vendor eclipse
Product open_vsx
Published 2026-06-23
Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N