eBay API MCP Server Affected by Environment Variable Injection
The ebay_set_user_tokens tool allows updating the .env file with new tokens. The updateEnvFile function in src/auth/oauth.ts blindly appends or replaces values without validating them for newlines or quotes. This allows an attacker to inject arbitrary environment variables into the configuration file.
Impact
An attacker can inject arbitrary environment variables into the .env file. This could lead to:
- Configuration Overwrites: Attackers can overwrite critical settings like
EBAY_REDIRECT_URIto hijack OAuth flows. - Denial of Service: Injecting invalid configuration can prevent the server from starting.
- Potential RCE: In some environments, controlling environment variables (like
NODE_OPTIONS) can lead to Remote Code Execution.
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Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | ebay-mcp | <= 1.7.2 | no fix |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H- Weakness (CWE)
CWE-15, CWE-74- Platform
- npm
- Package
ebay-mcp- Disclosed
- 19.02.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-97rm-xj73-33jh - CC BY 4.0
Vulnerability history: ebay-mcp
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
This is the only known vulnerability of this package.
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