CVE-2026-27203: Ebay mcp EBay API MCP Server Affected Vulnerability

HIGH
Advisory Identifier: GHSA-97rm-xj73-33jh
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CVSS 8.3
CWE-15 CWE-74
Published
Advisory Summary

CVE-2026-27203 is a HIGH (CVSS 8.3) ebay api mcp server affected vulnerability (CWE-15: External Control of System or Configuration Setting) affecting Ebay mcp libraries in the npm ecosystem. The issue involves ebay api mcp server affected by environment variable injection. Remediation is available in the latest vendor maintenance releases.

CVE-2026-27203 at a Glance

CVE Identifier CVE-2026-27203
GHSA Identifier GHSA-97rm-xj73-33jh
Severity HIGH
CVSS v3.1 Base Score 8.3
CWE Classification CWE-15: External Control of System or Configuration Setting
Affected Product Ebay mcp
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 8.3

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-27203

To remediate this vulnerability, upgrade all affected Ebay mcp dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

ebay-mcp fixed: Latest secure release 
npm install ebay-mcp@Latest secure release
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls ebay-mcp

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-27203, inspect your project dependencies using npm:

npm ls ebay-mcp

Analyze the terminal output to locate any version of Ebay mcp in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The npm ls ebay-mcp command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-15: External Control of System or Configuration Setting, where one or more system settings or configuration elements can be externally controlled by a user. In Ebay mcp, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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_URI` 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 `NODE_OPTIONS`) can lead to Remote Code Execution. Found with [MCPwner](https://github.com/Pigyon/MCPwner) 🕶

CVE-2026-27203 Affected Ebay mcp Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
ebay-mcp
npm/ebay-mcp
npm
≤ 1.7.2

References

GitHub Advisory / Wiki ADVISORY
https://github.com/YosefHayim/ebay-mcp/security/advisories/GHSA-97rm-xj73-33jh
NVD — CVE-2026-27203 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-27203
Security Fix Commit FIX COMMIT
https://github.com/YosefHayim/ebay-mcp/commit/aab0bda75ea9dd27aa37d0d8524d7cf41b3c4a9a
Ebay mcp Source Repository REPOSITORY
https://github.com/YosefHayim/ebay-mcp

Frequently Asked Questions

What is CVE-2026-27203?
CVE-2026-27203 is a security vulnerability in Ebay mcp involving eBay API MCP Server Affected by Environment Variable Injection under CWE-15: External Control of System or Configuration Setting.
Which Ebay mcp versions are affected?
Affected versions include releases prior to current release patches across affected packages: ebay-mcp.
What version fixes CVE-2026-27203?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is ebay-mcp affected?
Yes, ebay-mcp is affected in releases prior to Latest secure release. Upgrade your dependency to Latest secure release or later.
What is the CVSS score of CVE-2026-27203?
CVE-2026-27203 has a CVSS v3.1 base score of 8.3 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H.
What CWE is associated with CVE-2026-27203?
CVE-2026-27203 is classified under CWE-15: External Control of System or Configuration Setting (One or more system settings or configuration elements can be externally controlled by a user.).
How can I check npm dependencies for CVE-2026-27203?
Run the dependency tree command: 'npm ls ebay-mcp'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-97rm-xj73-33jh",
  "modified" : "2026-02-23T22:23:34Z",
  "published" : "2026-02-19T20:27:11Z",
  "aliases" : [ "CVE-2026-27203" ],
  "summary" : "eBay API MCP Server Affected by Environment Variable Injection ",
  "details" : "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.\n\n### Impact\nAn attacker can inject arbitrary environment variables into the `.env` file. This could lead to:\n- **Configuration Overwrites**: Attackers can overwrite critical settings like `EBAY_REDIRECT_URI` to hijack OAuth flows.\n- **Denial of Service**: Injecting invalid configuration can prevent the server from starting.\n- **Potential RCE**: In some environments, controlling environment variables (like `NODE_OPTIONS`) can lead to Remote Code Execution.\n\nFound with [MCPwner](https://github.com/Pigyon/MCPwner) 🕶",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "ebay-mcp"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "1.7.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/YosefHayim/ebay-mcp/security/advisories/GHSA-97rm-xj73-33jh"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-27203"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/YosefHayim/ebay-mcp/commit/aab0bda75ea9dd27aa37d0d8524d7cf41b3c4a9a"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/YosefHayim/ebay-mcp"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-15", "CWE-74" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-02-19T20:27:11Z",
    "nvd_published_at" : "2026-02-21T00:16:17Z"
  }
}