CVE-2026-27203 — HIGH (8.3)

Vulnerability Description

eBay API MCP Server is an open source local MCP server providing AI assistants with comprehensive access to eBay's Sell APIs. All versions are vulnerable to Environment Variable Injection through the updateEnvFile function. 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. An attacker can inject arbitrary environment variables into the .env file. This could lead to configuration overwrites, Denial of Service, and potential RCE. There was no fix for this issue at the time of publication.

CVSS Score

8.3

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality

LOW

Integrity

HIGH

Availability

HIGH

Related Weaknesses (CWE)

CWE-74 CWE-15

References

FAQ

What is CVE-2026-27203?

CVE-2026-27203 is a vulnerability with a CVSS score of 8.3 (HIGH). eBay API MCP Server is an open source local MCP server providing AI assistants with comprehensive access to eBay's Sell APIs. All versions are vulnerable to Environment Variable Injection through the ...

How severe is CVE-2026-27203?

CVE-2026-27203 has been rated HIGH with a CVSS base score of 8.3/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-27203?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.