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java-client Allows Network Pivot via Unvalidated directConnect Redirect in AppiumCommandExecutor

High severity GitHub Reviewed Published Jul 27, 2026 in appium/java-client

Package

maven io.appium:java-client (Maven)

Affected versions

>= 8.2.1, <= 10.1.0

Patched versions

10.1.1

Description

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:

1

Screenshot 2 — Java client processing response from attacker host:

2

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

References

@eglitise eglitise published to appium/java-client Jul 27, 2026
Published to the GitHub Advisory Database Jul 28, 2026
Reviewed Jul 28, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Changed
Confidentiality
High
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N

EPSS score

Weaknesses

Unintended Proxy or Intermediary ('Confused Deputy')

The product receives a request, message, or directive from an upstream component, but the product does not sufficiently preserve the original source of the request before forwarding the request to an external actor that is outside of the product's control sphere. This causes the product to appear to be the source of the request, leading it to act as a proxy or other intermediary between the upstream component and the external actor. Learn more on MITRE.

Server-Side Request Forgery (SSRF)

The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. Learn more on MITRE.

CVE ID

CVE-2026-43910

GHSA ID

GHSA-28f5-38xr-jh2w

Source code

Credits

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