Tool invocation via unrestricted HTTP host headers
Published Jan 7, 2026 · Updated Jan 7, 2026
DNS rebinding in Microsoft Playwright MCP before 0.0.40 allows remote attackers to invoke local MCP tools through a victim's browser. The HTTP transport processes requests without requiring the Host value to match the server's bound or explicitly allowed addresses. A malicious site or advertisement must induce the victim's browser to reach the running HTTP transport; accepted requests can execute every exposed tool without approval.
Summary
What happened
DNS rebinding in Microsoft Playwright MCP before 0.0.40 allows remote attackers to invoke local MCP tools through a victim's browser. The HTTP transport processes requests without requiring the Host value to match the server's bound or explicitly allowed addresses. A malicious site or advertisement must induce the victim's browser to reach the running HTTP transport; accepted requests can execute every exposed tool without approval.
The record
- CVE
- CVE-2025-9611
- Published
- Jan 7, 2026
- Updated
- Jan 7, 2026
- Vendor
- Microsoft
- Product
- Playwright MCP
- Classifications
- CWE-749, T1189
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 7, 2026CVE publishedPublication date reported by the CVE source.
- Jan 7, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <0.0.40
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- Playwright MCP DNS-rebinding initialization PoCproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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