CVE-2026-73683 — Laravel Socialite's Facebook provider contains an authentication bypass vulnerability…¶

Key facts

CVE-2026-73683 is a High (8.1) vulnerability: Laravel Socialite's Facebook provider contains an authentication bypass vulnerability…. This entry ships a detection-only PoC and a Docker test lab.


CVE	CVE-2026-73683
Severity	High (8.1)
Detection / prevention	—
PoC	poc.py
Source	2026/CVE-2026-73683/

Details¶

English | 한국어

Description¶

Laravel Socialite's Facebook provider contains an authentication bypass vulnerability that allows unauthenticated attackers to replay captured OIDC id_tokens by exploiting the missing nonce claim validation in the getUserByOIDCToken() function within FacebookProvider.php. Attackers who obtain a valid, unexpired id_token issued for the same Facebook App ID can submit the captured token to the backend userFromToken() endpoint, bypassing authentication controls because signature, aud, and iss checks pass while no session-bound nonce comparison is performed, resulting in unauthorized access to victim accounts.

Vulnerability Details¶

Property	Value
CVE ID	CVE-2026-73683
CVSS Score	8.1

Proof of Concept¶

Download¶

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-73683/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-2026-73683

# 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/laravel/socialite
https://github.com/laravel/socialite/commit/caf714f55d51ab0d914b40033d8b0f489d6219cc
https://github.com/laravel/socialite/pull/789
https://www.vulncheck.com/advisories/laravel-socialite-facebook-provider-authentication-bypass-via-nonce-replay

Generated by PoC Generator on 2026-08-15T09:08:05.313117299

Frequently asked questions¶

What is CVE-2026-73683?¶

CVE-2026-73683 is a High (8.1) vulnerability: Laravel Socialite's Facebook provider contains an authentication bypass vulnerability…. This entry ships a detection-only PoC and a Docker test lab.

How do I detect CVE-2026-73683?¶

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-2026-73683?¶

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.