Vulnerability · Published Jul 13, 2026 · Assigned by GitHub_M
CVE-2026-58500MCP Appium: Unescaped Locator Data XSS in MCP-UI Resource (createLocatorGeneratorUI)
High 8.2
In plain English
A high-severity cross-site scripting in appium-mcp from appium. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 34% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
MCP Appium is an MCP server that provides AI assistants with tools to automate mobile app testing on Android and iOS. In versions prior to 1.85.10, the createLocatorGeneratorUI function interpolates attacker-controlled element attributes — text, content-desc, resource-id, and locator selector values — directly into an HTML template literal without any HTML or JavaScript context escaping. An attacker who controls the UI of the app under test can inject arbitrary HTML and JavaScript into the MCP UI resource returned by the generate_locators tool. When a victim's MCP client renders this resource, the injected script executes and can invoke arbitrary MCP tools via window.parent.postMessage, leading to unauthorized MCP tool execution such as taking screenshots, reading page source, or any other registered capability. This issue has been fixed in version 1.85.10.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | appium-mcp | 1.85.10 | GHSA-x975-rgx4-5fh4 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| appium | appium-mcp | < 1.85.10 |
Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:N