CVE-2026-55089 — Etherpad is a real-time collaborative editor.¶
Key facts
CVE-2026-55089 is a Critical (9.9) vulnerability: Etherpad is a real-time collaborative editor.. This entry ships a detection-only PoC and a Docker test lab.
| CVE | CVE-2026-55089 |
| Severity | Critical (9.9) |
| Detection / prevention | — |
| PoC | poc.py |
| Source | 2026/CVE-2026-55089/ |
Details¶
English | 한국어
Description¶
Etherpad is a real-time collaborative editor. From 2.1.0 until 3.1.0, Etherpad's src/node/handler/APIHandler.ts authorizes requests to /api/2/* in the authorization_code OAuth path by using requiredClaims with the admin claim. This check requires only that the claim exists, while src/node/security/OAuth2Provider.ts issues admin: false for configured non-admin users. A non-admin user with a valid signed token can therefore invoke administrative functions including setHTML, setText, appendText, deletePad, copyPad, movePad, restoreRevision, anonymizeAuthor, listAllPads, and listAuthorsOfPad, allowing disclosure, modification, or deletion of pads across the instance. This issue is fixed in version 3.1.0.
Vulnerability Details¶
| Property | Value |
|---|---|
| CVE ID | CVE-2026-55089 |
| CVSS Score | 9.9 |
Proof of Concept¶
Download¶
# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-55089/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-2026-55089
# 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/ether/etherpad/commit/8c6104c5d5daf41f0d454acc04d42dffa0e0d996
- https://github.com/ether/etherpad/pull/7784
- https://github.com/ether/etherpad/releases/tag/v3.1.0
- https://github.com/ether/etherpad/security/advisories/GHSA-qfmh-fph3-mw8q
- https://github.com/ether/etherpad/security/advisories/GHSA-qfmh-fph3-mw8q
Generated by PoC Generator on 2026-08-23T20:44:43.598734723
Frequently asked questions¶
What is CVE-2026-55089?¶
CVE-2026-55089 is a Critical (9.9) vulnerability: Etherpad is a real-time collaborative editor.. This entry ships a detection-only PoC and a Docker test lab.
How do I detect CVE-2026-55089?¶
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-2026-55089?¶
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.