GHSA-28f5-38xr-jh2w

## Summary

When `directConnect(true)` is enabled, appium/java-client unconditionally accepts `directConnectHost`, `directConnectPort`, and `directConnectPath` from the server's NEW_SESSION response and silently redirects all subsequent session traffic to the attacker-specified endpoint — with no allowlist, no host validation, and no user notification.

## Affected Code

- `AppiumCommandExecutor.java` (line 196–219): `setDirectConnect()` builds a new URL from server-supplied fields and calls `overrideServerUrl(newUrl)` without validating host/IP. - `DirectConnect.java`: `getUrl()` constructs `protocol://host:port/path` with no allowlist.

## Root Cause

Only the protocol is validated (must equal "https"). The destination host and port are never checked against any allowlist or denylist.

## PoC (confirmed)

A rogue server injecting `directConnectHost=127.0.0.1:4443` causes the client to silently redirect all post-session commands:

[bootstrap] POST /wd/hub/session [bootstrap] Injecting directConnect -> https://127.0.0.1:4443/wd/hub [redirect-target] HIT #1: GET /wd/hub/session/poc-session-001/source [redirect-target] HIT #2: DELETE /wd/hub/session/poc-session-001

Original source code unmodified — confirmed via `git diff HEAD` (empty).

## Evidence Screenshots

**Screenshot 1 — Rogue server capturing redirected traffic:**

<img width="887" height="146" alt="1" src="https://github.com/user-attachments/assets/cc28002c-ea20-4ac8-8336-cec632e3c842" />

**Screenshot 2 — Java client processing response from attacker host:**

<img width="788" height="130" alt="2" src="https://github.com/user-attachments/assets/222cbab0-0d53-45b2-847d-6aa4e3b79370" />

## Impact

- Full interception of session traffic - Network pivot to internal hosts (RFC-1918, 169.254.169.254) - Cloud credential theft via IMDS endpoint - Escalates to ~8.1 High in CI/CD environments where directConnect(true) is set in shared base configuration

## Suggested Fix

Add allowlist validation before `overrideServerUrl()` is called, and/or block RFC-1918/loopback/link-local destinations by default.

[poc_appium_directconnect.zip](https://github.com/user-attachments/files/26472525/poc_appium_directconnect.zip)