GitHub Advisoryadvisory · Go
GHSA-7pf3-8xx7-rvhf MCP Toolbox for Databases vulnerable to DNS rebinding attacks
CRITICAL
Official page ↗
- Aliases
- CVE-2026-9739
- Ecosystem
- Go
- Packages
- github.com/googleapis/mcp-toolbox
- Severity
- Critical
- 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
- Weaknesses
- CWE-942
- Reviewed
- 2026-07-01
Affected packages
• Go github.com/googleapis/mcp-toolbox: < 1.2.0 → fixed in 1.2.0
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.
Related
Alias · CVE (1)
- CVE-2026-9739 Vulnerable to DNS rebinding attacks when using SSE (http://b/499408790). vulnerability
Weakness · CWE (1)
- CWE-942 Permissive Cross-domain Security Policy with Untrusted Domains weakness
References
- https://nvd.nist.gov/vuln/detail/CVE-2026-9739 advisory
- https://github.com/googleapis/mcp-toolbox/issues/3053 web
- https://github.com/googleapis/mcp-toolbox/pull/3054 web
- https://github.com/googleapis/mcp-toolbox/commit/c4c7bd917e686de68e2be866cfe3872c3439efae web
- https://github.com/googleapis/mcp-toolbox package