Admin-interface disclosure via unvalidated Host headers
Published Jun 3, 2026 · Updated Jun 3, 2026
DNS rebinding in Mercusys AC12G (EU) V1 firmware 200909 and 210128 allows remote attackers to read router admin responses. The HTTP server accepts arbitrary Host header values while every response carries Access-Control-Allow-Origin: *, allowing attacker-controlled JavaScript to pivot from a public domain to the router's private address and read returned content. Exploitation requires a LAN user to visit a malicious webpage; the flaw alone exposes admin-interface responses but does not establish configuration changes or service interruption.
Summary
What happened
DNS rebinding in Mercusys AC12G (EU) V1 firmware 200909 and 210128 allows remote attackers to read router admin responses. The HTTP server accepts arbitrary Host header values while every response carries Access-Control-Allow-Origin: *, allowing attacker-controlled JavaScript to pivot from a public domain to the router's private address and read returned content. Exploitation requires a LAN user to visit a malicious webpage; the flaw alone exposes admin-interface responses but does not establish configuration changes or service interruption.
The record
- CVE
- CVE-2026-36604
- Published
- Jun 3, 2026
- Updated
- Jun 3, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-350, T1185
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 3, 2026CVE publishedPublication date reported by the CVE source.
- Jun 3, 2026Record updatedLatest update available in the CVE record.
Exploitability
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Attacks
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