Vulnerable to DNS rebinding attacks when using SSE (http://b/499408790).
Priority MEDIUM 42CWE-942Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Active
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00279 20th percentileScored 2026-11-07
Fix Fixed MCP Toolbox for Databases (Google): PR 3054 (Fix CORS bypass)github.com/googleapis/mcp-toolbox (Go): 1.2.0
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| MCP Toolbox for Databases | before PR 3054 (Fix CORS bypass) | PR 3054 (Fix CORS bypass) | Patch available | CNA | |
| — | github.com/googleapis/mcp-toolbox (Go) | before 1.2.0 | 1.2.0 | Patch available | GHSA-7pf3-8xx7-rvhf |
- MCP Toolbox for Databases VendorGoogle Affected before PR 3054 (Fix CORS bypass) Fixed in PR 3054 (Fix CORS bypass) Patch available CNA
- github.com/googleapis/mcp-toolbox (Go) Vendor— Affected before 1.2.0 Fixed in 1.2.0 Patch available GHSA-7pf3-8xx7-rvhf
Remediation
- Fix · CNA MCP Toolbox for Databases (Google) Fixed in PR 3054 (Fix CORS bypass)
- Fix · GHSA-7pf3-8xx7-rvhf github.com/googleapis/mcp-toolbox (Go) Fixed in 1.2.0 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-9739
- 2026-10-03 Alias added: GHSA-7pf3-8xx7-rvhf
References
More Google vulnerabilities
- TI-2025-09686 Type confusion in Google Chrome KEVCVSS 3.1CRITICAL 9.8
- TI-2024-07390 Type confusion in Google Chrome KEVCVSS 3.1CRITICAL 9.6
- TI-2024-04898 Type confusion in Google Chrome KEVCVSS 3.1CRITICAL 9.6
- TI-2024-04600 Type confusion in Google Chrome KEVCVSS 3.1CRITICAL 9.6
- TI-2024-04346 Use after free in Google Chrome KEVCVSS 3.1CRITICAL 9.6
- TI-2023-05824 Integer overflow in Google Chrome KEVCVSS 3.1CRITICAL 9.6
Sources
- CVE-2026-9739 · CVE Program
- CVE-2026-9739 · NVD
- FIRST EPSS
- GHSA-7pf3-8xx7-rvhf · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences