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CVE-2026-18855 — The Link Library plugin for WordPress is vulnerable to arbitrary file deletion due to…

Key facts

CVE-2026-18855 is a Critical (9.1) vulnerability: The Link Library plugin for WordPress is vulnerable to arbitrary file deletion due to…. This entry ships a detection-only PoC and a Docker test lab.
CVE CVE-2026-18855
Severity Critical (9.1)
Detection / prevention —
PoC poc.py
Source 2026/CVE-2026-18855/

Details

English | 한국어

Description

The Link Library plugin for WordPress is vulnerable to arbitrary file deletion due to insufficient file path validation in the ll_delete_link_fields function in all versions up to, and including, 7.9.4 This makes it possible for unauthenticated attackers to delete arbitrary files on the server, which can easily lead to remote code execution when the right file is deleted (such as wp-config.php). Exploitation requires the administrator to have enabled the 'Delete local file on link deletion' plugin option (disabled by default) and to subsequently permanently delete the attacker-submitted link, which is a routine moderation action.

Vulnerability Details

Property Value
CVE ID CVE-2026-18855
Type RCE
CVSS Score 9.1

Proof of Concept

Download

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-18855/poc.py

Usage

# Run PoC against target
python3 poc.py --target <TARGET_URL>

# With authentication
python3 poc.py --target <TARGET_URL> --username <USER> --password <PASS>

⚠️ Warning: This PoC is for authorized security testing only. It uses detection-only techniques and does not exploit or damage target systems.

Test Lab

This repository includes a Docker-based test environment with both vulnerable and patched applications.

Quick Start

# Clone and navigate to CVE directory
cd CVE-2026-18855

# Start both applications
docker-compose up -d

# Run tests
./run-tests.sh    # Linux/Mac
./run-tests.ps1   # Windows PowerShell

Application Endpoints

Application URL Status
Vulnerable App http://localhost:8080 Shows vulnerability
Patched App http://localhost:8081 Demonstrates fix

Directory Structure

├── README.md           # English documentation
├── README_KO.md        # Korean documentation
├── poc.py              # PoC detection script
├── docker-compose.yml  # Container orchestration
├── run-tests.sh        # Linux/Mac test runner
├── run-tests.ps1       # Windows test runner
├── vulnerable-app/     # Vulnerable version
│   ├── app.py
│   ├── Dockerfile
│   └── requirements.txt
└── patched-app/        # Fixed version
    ├── app.py
    ├── Dockerfile
    └── requirements.txt

References

  • https://plugins.trac.wordpress.org/browser/link-library/tags/7.9.4/link-library-admin.php#L7865
  • https://plugins.trac.wordpress.org/browser/link-library/tags/7.9.4/link-library-admin.php#L7874
  • https://plugins.trac.wordpress.org/browser/link-library/tags/7.9.4/link-library.php#L2288
  • https://plugins.trac.wordpress.org/browser/link-library/tags/7.9.4/usersubmission.php#L476
  • https://plugins.trac.wordpress.org/browser/link-library/tags/7.9.4/usersubmission.php#L52
  • https://plugins.trac.wordpress.org/changeset/3646360/link-library/trunk/link-library-admin.php
  • https://plugins.trac.wordpress.org/changeset?old_path=%2Flink-library/tags/7.9.4&new_path=%2Flink-library/tags/7.9.5
  • https://plugins.trac.wordpress.org/changeset?reponame=&new=3646361%40link-library%2Ftags%2F7.9.5&old=3626573%40link-library%2Ftags%2F7.9.4
  • https://www.wordfence.com/threat-intel/vulnerabilities/id/41327dfa-db64-476a-a263-7bd4f69fb857?source=cve

Generated by PoC Generator on 2026-08-16T04:48:38.451514142

Frequently asked questions

What is CVE-2026-18855?

CVE-2026-18855 is a Critical (9.1) vulnerability: The Link Library plugin for WordPress is vulnerable to arbitrary file deletion due to…. This entry ships a detection-only PoC and a Docker test lab.

How do I detect CVE-2026-18855?

Run the detection-only PoC included with this entry against your Docker test lab to confirm whether a target is affected; pair it with your own IDS logging.

How do I block or mitigate CVE-2026-18855?

Upgrade to a fixed version per the vendor advisory; the NVD record lists the affected versions. Use the included PoC to verify your remediation.

For authorized security testing and research only. See the full source and NVD record.