# CVE-2026-58500: MCP Appium: Unescaped Locator Data XSS in MCP-UI Resource (createLocatorGeneratorUI)

> Attackers can inject scripts via mobile app UI attributes, leading to arbitrary JavaScript execution and unauthorized MCP tool invocation in the Appium MCP server.

- **Severity:** High 8.2 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 13 Jul 2026
- **Updated:** 14 Jul 2026
- **Also known as:** GHSA-x975-rgx4-5fh4

## What is CVE-2026-58500?

CVE-2026-58500 is a high-severity cross-site scripting vulnerability in appium-mcp, published on 13 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### 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.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-58500?

2 open source packages ship an affected version, including appium-mcp. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `appium-mcp` | npm | All versions | 1.85.10 |
| `appium-mcp` | npm | All versions | 1.85.10 |

Products: Appium Appium-Mcp.

## How do I fix CVE-2026-58500?

Upgrade appium-mcp to 1.85.10 or later.

## Is CVE-2026-58500 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-58500 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-58500 and fix it if it is affected.

What it is: CVE-2026-58500 is a high-severity cross-site scripting vulnerability in appium-mcp, published on 13 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-58500 exists.

Affected packages and fixed versions:
- appium-mcp (npm): affected all versions; fixed in 1.85.10
- appium-mcp (npm): affected all versions; fixed in 1.85.10

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-58500/ (Markdown: https://insights.sbomify.com/CVE-2026-58500/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-58500
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-58500
- OSV: https://osv.dev/vulnerability/CVE-2026-58500

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-58500/
Summaries are generated and may contain mistakes; the official description above is the record.