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CVE-2026-80349 — TarsWeb decides whether a request comes from a trusted local caller using a…

Key facts

CVE-2026-80349 is a Critical (9.8) vulnerability: TarsWeb decides whether a request comes from a trusted local caller using a…. This entry ships a detection-only PoC and a Docker test lab.
CVE CVE-2026-80349
Severity Critical (9.8)
Detection / prevention —
PoC poc.py
Source 2026/CVE-2026-80349/

Details

English | 한국어

Description

TarsWeb decides whether a request comes from a trusted local caller using a client-controlled header. app.js sets Koa's proxy option to true without naming which upstream proxies may be trusted and without limiting the number of forwarded hops, so the request address Koa reports is taken from the X-Forwarded-For header supplied by the caller. In midware/ssoMidware.js a single branch covers both the ignored-path list and the ignoreIps allowlist from config/loginConf.js, which contains the loopback address, and that branch assigns the effective account identity from the uid query parameter before falling through to the request without validating any ticket, cookie or password. A request carrying a forged X-Forwarded-For value naming the loopback address and a uid naming an existing account therefore reaches every route the console mounts as that account, including an administrator, with no credential of any kind. Those routes include user and role administration, service configuration, and package upload and deployment. Version 3.0.16 separates the two branches so that a match on the address allowlist assigns the configured default account rather than one named by the caller.

Vulnerability Details

Property Value
CVE ID CVE-2026-80349
CVSS Score 9.8

Proof of Concept

Download

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-80349/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-2026-80349

# 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/TarsCloud/TarsWeb
  • https://github.com/TarsCloud/TarsWeb/blob/v3.0.14/app.js
  • https://github.com/TarsCloud/TarsWeb/blob/v3.0.14/midware/ssoMidware.js
  • https://github.com/TarsCloud/TarsWeb/issues/212
  • https://www.vulncheck.com/advisories/tarsweb-through-3.0.14-authentication-bypass-via-spoofed-x-forwarded-for-and-uid-parameter
  • https://github.com/TarsCloud/TarsWeb/issues/212

Generated by PoC Generator on 2026-08-30T22:39:59.823188901

Frequently asked questions

What is CVE-2026-80349?

CVE-2026-80349 is a Critical (9.8) vulnerability: TarsWeb decides whether a request comes from a trusted local caller using a…. This entry ships a detection-only PoC and a Docker test lab.

How do I detect CVE-2026-80349?

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-2026-80349?

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.