CVE-2026-9739

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.

Affected Software

VendorProductVersion RangeStatus
GoogleMCP Toolbox for Databases0 < PR 3054 (Fix CORS bypass)affected

Weaknesses

  • CWE-942: CWE-942: Permissive Cross-domain Policy with Untrusted Domains

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: total

References