eBay API MCP Server Affected by Environment Variable Injection

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-27203: 0.40% estimated exploitation activity in the next 30 days; percentile 34.41 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

The ebaysetusertokens 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 EBAYREDIRECTURI to hijack OAuth flows. - Denial of Service: Injecting invalid configuration can prevent the server from starting. - Potential RCE: In some environments, controlling environment variables (like NODEOPTIONS) can lead to Remote Code Execution. Found with MCPwner 🕶

Published by the source

19 Feb 2026, 20:27 UTC

Last modified by the source

23 Feb 2026, 23:43 UTC

Source last checked

26 Oct 2026, 12:42 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-97rm-xj73-33jh

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-97rm-xj73-33jh

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# Patch Next advisory brief: CVE-2026-27203

Advisory: eBay API MCP Server Affected by Environment Variable Injection
IDs: CVE-2026-27203, GHSA-97rm-xj73-33jh
Record: https://patchnext.com/advisories/cve-2026-27203 (revision 2, source checked 26 Oct 2026, 12:42 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm ebay-mcp: affected <= 1.7.2

## Suggested inspection (read-only)
- `npm ls ebay-mcp --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on ebay-mcp.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-97rm-xj73-33jh (OSV record GHSA-97rm-xj73-33jh lists affected ranges: npm ebay-mcp >=0 <=1.7.2)
- Verified: https://github.com/advisories/GHSA-97rm-xj73-33jh (GitHub-reviewed advisory GHSA-97rm-xj73-33jh lists affected ranges: npm ebay-mcp >=0 <=1.7.2)

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