CVE-2026-27203Network attack vector

Authenticated configuration overwrite via newline injection

Published Feb 20, 2026 · Updated Feb 20, 2026

Environment variable injection in eBay MCP 1.7.2 and earlier allows remote authenticated users to overwrite .env settings via token values. The updateEnvFile function in src/auth/oauth.ts embeds unvalidated newlines and quotes from ebay_set_user_tokens into hand-built key-value lines. Access to that tool permits OAuth redirect changes or a restart failure; code execution additionally requires a runtime-sensitive variable such as NODE_OPTIONS.

CVSS severity8.3
High
EPSS probability0.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Environment variable injection in eBay MCP 1.7.2 and earlier allows remote authenticated users to overwrite .env settings via token values. The updateEnvFile function in src/auth/oauth.ts embeds unvalidated newlines and quotes from ebay_set_user_tokens into hand-built key-value lines. Access to that tool permits OAuth redirect changes or a restart failure; code execution additionally requires a runtime-sensitive variable such as NODE_OPTIONS.

The record

CVE
CVE-2026-27203
Published
Feb 20, 2026
Updated
Feb 20, 2026
Vendor
Yosef Hayim Sabag
Product
eBay MCP
Classifications
CWE-74, CWE-15, CWE-20, T1565.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=<= 1.7.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Yosef Hayim Sabag · eBay MCPversion=<= 1.7.2

Published CVSS scores

8.3GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
CWE-15External Control of System or Configuration Setting
CWE-20Improper Input Validation
T1565.001Stored Data Manipulation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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