CVE-2026-9739
Vulnerable to DNS rebinding attacks when using SSE (http://b/499408790). During the beta phase, we implemented `allowed-origins` and `allowed-hosts` flags to align with MCP security guidelines. However, the hardcoded `Access-Control-Allow-Origin: *` header in the SSE initialization handler was inadvertently retained. This vulnerability specifically impacts users connecting via Toolbox using SSE under specification v2024-11-05.
Scoring
- Severity
- CRITICAL
- CVSS base score
- 9.4
- CVSS vector
- CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
- EPSS probability
- 0.28%
- CWE
- CWE-942
- Published
- 2026-05-27
- Last modified
- 2026-05-28
Affected products
- Google MCP Toolbox for Databases
Weakness type
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