CVE
CVE-2026-27203
eBay API MCP Server Affected by Environment Variable Injection
The ebaysetuser_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
EBAYREDIRECTURIto 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.
Found with MCPwner 🕶
Package Versions Affected
Package Version
patch Availability
No items found.
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CVSS Version
Severity
Base Score
CVSS Version
Score Vector
C
H
U
8.3
-
3.1
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H
C
H
U
0
-
3.1
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H
C
H
U
-
Related Resources
No items found.
References
https://github.com/YosefHayim/ebay-mcp/security/advisories/GHSA-97rm-xj73-33jh, https://nvd.nist.gov/vuln/detail/CVE-2026-27203, https://github.com/YosefHayim/ebay-mcp/commit/aab0bda75ea9dd27aa37d0d8524d7cf41b3c4a9a, https://github.com/YosefHayim/ebay-mcp
Basic Information
Ecosystem
