eBay API MCP Server Affected by Environment Variable Injection

published 2026-02-19 8 mo ago modified 2026-06-17 4 mo ago also GHSA-97rm-xj73-33jh , EUVD-2026-7748

cvss: 8.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 34%
public exploits: 0; none known

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.

Patch / fix

links 1

github.com/YosefHayim/ebay-mcp@aab0bda commit

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 8 mo ago (2026-02-25)

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 34% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	8.3	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H
GitHub	3.1	8.3	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H

Affected packages

ecosystem	package	affected	fixed in
npm	ebay-mcp	<=1.7.2	no fix listed

Affected products

YosefHayim ebay-mcp

Classification

Weakness

CWE-15 External Control of System or Configuration Setting
CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary