CVE-2026-83627 — The Hummingbird – Speed Optimization, Caching, Minify, Compress & CDN plugin for…¶
Key facts
CVE-2026-83627 is a Critical (9.8) vulnerability: The Hummingbird – Speed Optimization, Caching, Minify, Compress & CDN plugin for…. This entry ships a detection-only PoC and a Docker test lab.
| CVE | CVE-2026-83627 |
| Severity | Critical (9.8) |
| Detection / prevention | — |
| PoC | poc.py |
| Source | 2026/CVE-2026-83627/ |
Details¶
English | 한국어
Description¶
The Hummingbird – Speed Optimization, Caching, Minify, Compress & CDN plugin for WordPress is vulnerable to Remote Code Execution in all versions up to, and including, 3.21.0 via the log_msg() function in core/modules/class-page-cache.php. The page-cache debug log is written to wp-content/wphb-logs/page-caching-log.php, a directly web-accessible PHP file that is supposed to be protected by a leading '' header. That header is guarded by class_exists( 'Filesystem' ), which can never match because class_exists() resolves string arguments in the global namespace while the class is Hummingbird\Core\Filesystem; when the log is created during a front-end request the header is therefore omitted entirely. get_cookies() then writes the raw name of any cookie matching the wphb_cache_ prefix into that file without sanitization. This makes it possible for unauthenticated attackers to write arbitrary PHP into the log file with a single anonymous request and execute it by requesting the file directly, resulting in full remote code execution. Exploitation requires the site administrator to have enabled Page Caching with the Debug Log option (non-default), and the log file to be created during a front-end request — a state reached by the plugin's own 'Clear logs' action, any cache flush, or unattended via the plugin's daily log-rotation cron, which can strip the protective header from an existing log file.
Vulnerability Details¶
| Property | Value |
|---|---|
| CVE ID | CVE-2026-83627 |
| Type | RCE |
| CVSS Score | 9.8 |
Proof of Concept¶
Download¶
# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-83627/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-2026-83627
# 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/hummingbird-performance/trunk/core/modules/class-page-cache.php#L1973
- https://plugins.trac.wordpress.org/browser/hummingbird-performance/trunk/core/modules/class-page-cache.php#L1982
- https://plugins.trac.wordpress.org/browser/hummingbird-performance/trunk/core/modules/class-page-cache.php#L749
- https://plugins.trac.wordpress.org/browser/hummingbird-performance/trunk/core/modules/class-page-cache.php#L752
- https://plugins.trac.wordpress.org/changeset/3675836/hummingbird-performance/trunk/core/modules/class-page-cache.php
- https://plugins.trac.wordpress.org/changeset?old_path=%2Fhummingbird-performance/tags/3.20.0&new_path=%2Fhummingbird-performance/tags/3.21.2
- https://plugins.trac.wordpress.org/changeset?reponame=&new=3675836%40hummingbird-performance%2Ftags%2F3.21.2&old=3614991%40hummingbird-performance%2Ftags%2F3.20.0
- https://www.wordfence.com/threat-intel/vulnerabilities/id/65c3ca36-79e6-47f8-9524-27e7631f4caf?source=cve
Generated by PoC Generator on 2026-09-06T02:11:20.667237679
Frequently asked questions¶
What is CVE-2026-83627?¶
CVE-2026-83627 is a Critical (9.8) vulnerability: The Hummingbird – Speed Optimization, Caching, Minify, Compress & CDN plugin for…. This entry ships a detection-only PoC and a Docker test lab.
How do I detect CVE-2026-83627?¶
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-2026-83627?¶
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.