CVE-2026-27203
eBay API MCP Server Affected by Environment Variable Injection
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
eBay API MCP Server Affected by Environment Variable Injection
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.
- Record
CVE-2026-27203- CVSS 3.1
- 8.3 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H - Weakness
- CWE-15, CWE-74
- Updated
- 2026-11-02
EUVDEUVD-2026-7748
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.
- Record
EUVD-2026-7748- CVSS 3.1
- 8.3 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-97rm-xj73-33jh
eBay API MCP Server Affected by Environment Variable Injection
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_URIto 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 🕶
- Record
GHSA-97rm-xj73-33jh- CVSS 3.1
- 8.3 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H - Weakness
- CWE-15, CWE-74
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2026-27203- CVSS 3.1
- 8.3 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H - Weakness
- CWE-15, CWE-74
- Updated
- 2026-11-02
OSV
eBay API MCP Server Affected by Environment Variable Injection
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.
- Record
CVE-2026-27203- CVSS 3.1
- 8.3 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H - Weakness
- CWE-15, CWE-74
- Updated
- 2026-11-02
OSVGHSA-97rm-xj73-33jh
eBay API MCP Server Affected by Environment Variable Injection
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_URIto 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 🕶
- Record
GHSA-97rm-xj73-33jh- CVSS 3.1
- 8.3 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H - Weakness
- CWE-15, CWE-74
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
ebay-mcpnpm | through 1.7.2 | None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-27203 is a high vulnerability (CVSS 8.3) in Yosefhayim Ebay-mcp, published February 19, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.40%, the 34th percentile. No source names a fixed version.
References
github.com/YosefHayim/ebay-mcp/security/advisories/GHSA-97rm-xj73-33jh
nvd.nist.gov/vuln/detail/CVE-2026-27203