CVE-2026-27203
eBay API MCP Server Affected by Environment Variable Injection
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.
INFO
Published Date :
Feb. 21, 2026, 12:16 a.m.
Last Modified :
Feb. 21, 2026, 12:16 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-27203
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Sanitize all user-supplied input before appending to .env.
- Validate input for newline characters and quotes.
- Implement strict input validation rules.
- Review and update the updateEnvFile function.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-27203.
| URL | Resource |
|---|---|
| https://github.com/YosefHayim/ebay-mcp/commit/aab0bda75ea9dd27aa37d0d8524d7cf41b3c4a9a | |
| https://github.com/YosefHayim/ebay-mcp/security/advisories/GHSA-97rm-xj73-33jh |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-27203 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-27203
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-27203 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-27203 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Feb. 21, 2026
Action Type Old Value New Value Added 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. Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H Added CWE CWE-74 Added CWE CWE-15 Added Reference https://github.com/YosefHayim/ebay-mcp/commit/aab0bda75ea9dd27aa37d0d8524d7cf41b3c4a9a Added Reference https://github.com/YosefHayim/ebay-mcp/security/advisories/GHSA-97rm-xj73-33jh