CVE-2026-9739
- State
- Published
- Severity
- 9.4 Critical
- Published
- May 27, 2026
- Updated
- May 28, 2026
- Reserved
- May 27, 2026
Description
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 9.4 Critical | 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 |
Weaknesses
- CWE-942 Permissive Cross-domain Policy with Untrusted Domains
Affected Products
| Product | Versions |
|---|---|
MCP Toolbox for DatabasesGoogle |
|
References
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