CRITICAL CVSS 9.0
Published: 2026-01-22

CVE-2026-23873

hustoj hustoj Security Advisory (CVE-2026-23873)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-23873 impacting hustoj hustoj. Evaluated with CVSS Base Score of 9.0 (CRITICAL).

Original NVD Description

Source: NIST NVD
hustoj is an open source online judge based on PHP/C++/MySQL/Linux for ACM/ICPC and NOIP training. All versions are vulnerable to CSV Injection (Formula Injection) through the contest rank export functionality (contestrank.xls.php and admin/ranklist_export.php). The application fails to sanitize user-supplied input (specifically the "Nickname" field) before exporting it to an .xls file (which renders as an HTML table but is opened by Excel). If a malicious user sets their nickname to an Excel formula when an administrator exports and opens the rank list in Microsoft Excel, the formula will be executed. This can lead to arbitrary command execution (RCE) on the administrator's machine or data exfiltration. A fix was not available at the time of publication.

📊 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
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 hustoj / hustoj
Affected Versions *
Weakness Enumeration CWE-1236

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-2026-23873 impacting hustoj hustoj.

⚡ Nuclei Detection Template (YAML) cve-2026-23873.yaml
id: cve-2026-23873

info:
  name: hustoj hustoj - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: critical
  description: |
    Automated signature & scanner for CVE-2026-23873 affecting hustoj hustoj.
    Evaluation: hustoj is an open source online judge based on PHP/C++/MySQL/Linux for ACM/ICPC and NOIP training. All versions are vulnerable to CSV Injection (Formu...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-23873
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
    cvss-score: 9.0
    cve-id: CVE-2026-23873
    cwe-id: CWE-1236
  tags: cve,cve-2026-23873,hustoj,hustoj,critical

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "hustoj"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-23873.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-23873
# Target: hustoj hustoj | CVSS: 9.0 (CRITICAL)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-23873 (hustoj hustoj)...")
    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 hustoj hustoj 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-2026-23873.sh
# Recommended Remediation & Patching Commands for CVE-2026-23873
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install hustoj 2>/dev/null || \
sudo dnf upgrade hustoj 2>/dev/null || \
sudo yum update hustoj

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

# 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-2026-23873 in hustoj hustoj?

Review vendor-specific security notices and update hustoj hustoj 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-2026-23873?

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-2026-23873?

CVE-2026-23873 is classified with a CVSS 3.1 Base Score of 9.0 (CRITICAL). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
9.0
CRITICAL SEVERITY
CVE ID CVE-2026-23873
Weakness CWE-1236
Vendor hustoj
Product hustoj
Published 2026-01-22
Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H