CVE-2026-9739 – Google Chrome SSE DNS Rebinding

CVE ID :CVE-2026-9739

Published : May 27, 2026, 11:16 p.m. | 1 hour, 15 minutes ago

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.

Severity: 9.4 | CRITICAL

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