CVE-2026-63135 — YOURLS is a self-hosted, customizable URL shortener written in PHP.¶

Key facts

CVE-2026-63135 is a High (8.2) vulnerability: YOURLS is a self-hosted, customizable URL shortener written in PHP.. This entry ships a detection-only PoC and a Docker test lab.


CVE	CVE-2026-63135
Severity	High (8.2)
Detection / prevention	—
PoC	poc.py
Source	2026/CVE-2026-63135/

Details¶

English | 한국어

Description¶

YOURLS is a self-hosted, customizable URL shortener written in PHP. From 1.5.1 until 1.10.4, YOURLS stores the HTTP Referer header through yourls_get_referrer(), yourls_sanitize_url_safe(), and yourls_log_redirect(), then aggregates the value in yourls-infos.php and passes the derived domain through yourls_get_domain(), yourls_stats_pie(), and yourls_google_array_to_data_table(). The chart builder concatenates labels into inline JavaScript without JavaScript-string escaping, so an unauthenticated attacker can poison the statistics of an existing short URL with a crafted referrer. When an administrator or public stats-page viewer opens the affected statistics page, attacker-controlled JavaScript executes in the YOURLS origin and can access admin-visible data, the API signature token, and privileged same-origin actions. This issue is fixed in version 1.10.4.

Vulnerability Details¶

Property	Value
CVE ID	CVE-2026-63135
Type	XSS
CVSS Score	8.2

Proof of Concept¶

Download¶

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-63135/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-2026-63135

# 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://github.com/YOURLS/YOURLS/commit/e1e93476655107e6caab34e52259eb1c91079ec7
https://github.com/YOURLS/YOURLS/pull/4107
https://github.com/YOURLS/YOURLS/releases/tag/1.10.4
https://github.com/YOURLS/YOURLS/security/advisories/GHSA-5h77-88j3-r659

Generated by PoC Generator on 2026-08-22T09:06:52.69452821

Frequently asked questions¶

What is CVE-2026-63135?¶

CVE-2026-63135 is a High (8.2) vulnerability: YOURLS is a self-hosted, customizable URL shortener written in PHP.. This entry ships a detection-only PoC and a Docker test lab.

How do I detect CVE-2026-63135?¶

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-2026-63135?¶

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.