CRITICAL CVSS 9.8
Published: 2026-02-11

CVE-2026-26021

set-in_project set-in Security Advisory (CVE-2026-26021)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-26021 impacting set-in_project set-in. Evaluated with CVSS Base Score of 9.8 (CRITICAL).

Original NVD Description

Source: NIST NVD
set-in provides the set value of nested associative structure given array of keys. A prototype pollution vulnerability exists in the the npm package set-in (>=2.0.1, < 2.0.5). Despite a previous fix that attempted to mitigate prototype pollution by checking whether user input contained a forbidden key, it is still possible to pollute Object.prototype via a crafted input using Array.prototype. This has been fixed in version 2.0.5.

📊 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
None (PR:N)
Unauthenticated execution
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 set-in_project / set-in
Affected Versions *
Weakness Enumeration CWE-1321

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-2026-26021 impacting set-in_project set-in.

⚡ Nuclei Detection Template (YAML) cve-2026-26021.yaml
id: cve-2026-26021

info:
  name: set-in_project set-in - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: critical
  description: |
    Automated signature & scanner for CVE-2026-26021 affecting set-in_project set-in.
    Evaluation: set-in provides the set value of nested associative structure given array of keys. A prototype pollution vulnerability exists in the the npm package s...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-26021
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 9.8
    cve-id: CVE-2026-26021
    cwe-id: CWE-1321
  tags: cve,cve-2026-26021,set-in_project,set-in,critical

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "set-in"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-26021.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-26021
# Target: set-in_project set-in | CVSS: 9.8 (CRITICAL)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-26021 (set-in_project set-in)...")
    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 set-in_project set-in 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-2026-26021.sh
# Recommended Remediation & Patching Commands for CVE-2026-26021
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install set-in 2>/dev/null || \
sudo dnf upgrade set-in 2>/dev/null || \
sudo yum update set-in

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

# 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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Distributions
  • No records filed in this category.

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-26021 in set-in_project set-in?

Review vendor-specific security notices and update set-in_project set-in 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-2026-26021?

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-2026-26021?

CVE-2026-26021 is classified with a CVSS 3.1 Base Score of 9.8 (CRITICAL). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
9.8
CRITICAL SEVERITY
CVE ID CVE-2026-26021
Weakness CWE-1321
Vendor set-in_project
Product set-in
Published 2026-02-11
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H