CVE-2026-53516 — Better Auth is an authentication and authorization library for TypeScript.¶
Key facts
CVE-2026-53516 is a High (8.3) vulnerability: Better Auth is an authentication and authorization library for TypeScript.. This entry ships a detection-only PoC and a Docker test lab.
| CVE | CVE-2026-53516 |
| Severity | High (8.3) |
| Detection / prevention | — |
| PoC | poc.py |
| Source | 2026/CVE-2026-53516/ |
Details¶
English | 한국어
Description¶
Better Auth is an authentication and authorization library for TypeScript. Prior to 1.6.11, Better Auth's OAuth callback auto-link gate in handleOAuthUserInfo accepts implicit account linking when the OAuth provider asserts email_verified: true without requiring the local user row's emailVerified field to also be true, allowing an attacker who pre-registers a victim email through /sign-up/email to bind the victim's OAuth identity to the attacker's account. The same primitive affects one-tap, and emailAndPassword.requireEmailVerification: true does not mitigate the link-time verification change. This issue is fixed in version 1.6.11.
Vulnerability Details¶
| Property | Value |
|---|---|
| CVE ID | CVE-2026-53516 |
| CVSS Score | 8.3 |
Proof of Concept¶
Download¶
# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-53516/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-2026-53516
# 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/better-auth/better-auth/commit/da7e50beee849c59a2ed1ec6b3a38cc6ab9fb563
- https://github.com/better-auth/better-auth/pull/9578
- https://github.com/better-auth/better-auth/releases/tag/v1.6.11
- https://github.com/better-auth/better-auth/security/advisories/GHSA-g38m-r43w-p2q7
Generated by PoC Generator on 2026-07-16T06:28:33.794220629
Frequently asked questions¶
What is CVE-2026-53516?¶
CVE-2026-53516 is a High (8.3) vulnerability: Better Auth is an authentication and authorization library for TypeScript.. This entry ships a detection-only PoC and a Docker test lab.
How do I detect CVE-2026-53516?¶
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-2026-53516?¶
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.