CVE-2026-27203 eBay API MCP Server Affected by Environment Variable Injection
Attackers can inject arbitrary environment variables via the token update tool, potentially leading to remote code execution or denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-27203?
CVE-2026-27203 is a high-severity code injection vulnerability in YosefHayim ebay-mcp, published on 20 Feb 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-27203?
2 open source packages ship an affected version, including ebay-mcp.
| Package | Affected | Fixed in |
|---|---|---|
ebay-mcp npm | All versions to 1.7.2 | None |
ebay-mcp npm | All versions to 1.7.2 | None |
How do I fix CVE-2026-27203?
No fix has been published for CVE-2026-27203 yet. Limit exposure of the affected software until one is available.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-27203 being exploited?
There is no known exploitation of CVE-2026-27203 in the wild and no public exploit code.
Sources
Also known as GHSA-97rm-xj73-33jh.