CVE-2026-27203

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{"affected": [{"affectedData": [{"product": "ebay-mcp", "vendor": "YosefHayim", "versions": [{"status": "affected", "version": "<= 1.7.2"}]}], "source": "security-advisories@github.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}, {"lang": "es", "value": "eBay API MCP Server es un servidor MCP local de c\u00f3digo abierto que proporciona a los asistentes de IA acceso completo a las API de venta de eBay. Todas las versiones son vulnerables a la Inyecci\u00f3n de Variables de Entorno a trav\u00e9s de la funci\u00f3n updateEnvFile. La herramienta ebay_set_user_tokens permite actualizar el archivo .env con nuevos tokens. La funci\u00f3n updateEnvFile en src/auth/oauth.ts a\u00f1ade o reemplaza valores ciegamente sin validarlos en busca de saltos de l\u00ednea o comillas. Esto permite a un atacante inyectar variables de entorno arbitrarias en el archivo de configuraci\u00f3n. Un atacante puede inyectar variables de entorno arbitrarias en el archivo .env. Esto podr\u00eda llevar a sobrescrituras de configuraci\u00f3n, Denegaci\u00f3n de Servicio y potencial RCE. No hab\u00eda una soluci\u00f3n para este problema en el momento de la publicaci\u00f3n."}], "id": "CVE-2026-27203", "lastModified": "2026-06-17T10:26:50.467", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.3, "baseSeverity": "HIGH", "confidentialityImpact": "LOW", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 5.5, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-27203", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-02-25T21:29:04.945257Z", "version": "2.0.3"}}]}, "published": "2026-02-21T00:16:17.463", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/YosefHayim/ebay-mcp/commit/aab0bda75ea9dd27aa37d0d8524d7cf41b3c4a9a"}, {"source": "security-advisories@github.com", "url": "https://github.com/YosefHayim/ebay-mcp/security/advisories/GHSA-97rm-xj73-33jh"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Deferred", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-15"}, {"lang": "en", "value": "CWE-74"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,1.7.2]"}}], "enrichment": {"confidence": 100.0, "confidence_source": "cna", "scores": [{"score": 100.0, "source": "cna"}]}, "original": {"product": "ebay-mcp", "source": "cna", "vendor": "YosefHayim"}, "product": "ebay-mcp", "vendor": "yosefhayim"}], "analysis": {"en": {"generated_at": "2026-04-17T16:58:28.492709+00:00", "value": {"mitigation_remediation": ["Disable or restrict use of the ebay_set_user_tokens tool until an official fix is available.", "Manually audit and clean the .env file to remove any unauthorized variables, and apply strict input validation when adding new entries.", "Apply the vendor\u2019s patch or upgrade to the latest version of eBay API MCP Server as soon as it is released and monitor the project's security advisories for further information."], "summary": {"action": "Assess Impact", "impact": "Remote Code Execution via environment variable injection"}, "threat_synthesis": {"affected_systems": "All releases of the open\u2011source eBay API MCP Server provided by the developer YosefHayim are affected. The issue exists in the src/auth/oauth.ts module of the project, and applies to every version that has not yet been patched by the maintainer. No specific product version ranges are listed, so any deployment of ebay\u2011mcp that incorporates the unauthenticated updateEnvFile function remains vulnerable.", "description_and_impact": "The vulnerability in the eBay API MCP Server allows attackers to inject arbitrary environment variables into the server\u2019s .env configuration file by exploiting how the updateEnvFile function processes input from the ebay_set_user_tokens tool. This environment variable injection can overwrite critical configuration values, potentially leading to configuration tampering, denial of service, or, in the worst case, remote code execution if the injected variables influence executable code paths. The flaw is a classic case of uncontrolled input leading to improper handling of environment data, classified under CWE\u201115 (Improper Handling of Environment Variables) and CWE\u201174 (Improper Validation of String or Buffer).", "risk_and_exploitability": "This flaw carries a CVSS v3.1 score of 8.3, indicating a high severity. The EPSS score is listed as less than 1%, implying a very low probability of exploitation in the wild, and the vulnerability is not yet catalogued in the CISA KEV list. In practice an attacker would need to gain some form of execution or influence over the ebay_set_user_tokens utility or the input it consumes; the most likely attack vector is local or privileged access that allows modification of the .env file or injection of malformed data via the tool. Because the flaw permits arbitrary environment variables to be written, the risk escalates if an attacker can subsequently trigger those variables in a context that leads to code execution."}}}}, "created": "2026-02-23T14:33:01.570109+00:00", "updated": "2026-04-17T17:00:10.204558+00:00", "vendors": ["yosefhayim", "yosefhayim$PRODUCT$ebay-mcp"]}